So I was able to do this. I created a separate project use EF Core and just put my data layer in there. It's much easier to keep the data separate and EF makes it easy to reference. Here are the references for my NET Framework project:
<Reference Include="Microsoft.Bcl.AsyncInterfaces, Version=1.0.0.0, Culture=neutral, PublicKeyToken=cc7b13ffcd2ddd51, processorArchitecture=MSIL">
<HintPath>..\packages\Microsoft.Bcl.AsyncInterfaces.1.1.0\lib\net461\Microsoft.Bcl.AsyncInterfaces.dll</HintPath>
</Reference>
<Reference Include="Microsoft.Bcl.HashCode, Version=1.0.0.0, Culture=neutral, PublicKeyToken=cc7b13ffcd2ddd51, processorArchitecture=MSIL">
<HintPath>..\packages\Microsoft.Bcl.HashCode.1.1.0\lib\net461\Microsoft.Bcl.HashCode.dll</HintPath>
</Reference>
<Reference Include="Microsoft.Data.SqlClient, Version=1.0.19269.1, Culture=neutral, PublicKeyToken=23ec7fc2d6eaa4a5, processorArchitecture=MSIL">
<HintPath>..\packages\Microsoft.Data.SqlClient.1.0.19269.1\lib\net46\Microsoft.Data.SqlClient.dll</HintPath>
</Reference>
<Reference Include="Microsoft.EntityFrameworkCore, Version=3.1.1.0, Culture=neutral, PublicKeyToken=adb9793829ddae60, processorArchitecture=MSIL">
<HintPath>..\packages\Microsoft.EntityFrameworkCore.3.1.1\lib\netstandard2.0\Microsoft.EntityFrameworkCore.dll</HintPath>
</Reference>
<Reference Include="Microsoft.EntityFrameworkCore.Abstractions, Version=3.1.1.0, Culture=neutral, PublicKeyToken=adb9793829ddae60, processorArchitecture=MSIL">
<HintPath>..\packages\Microsoft.EntityFrameworkCore.Abstractions.3.1.1\lib\netstandard2.0\Microsoft.EntityFrameworkCore.Abstractions.dll</HintPath>
</Reference>
<Reference Include="Microsoft.EntityFrameworkCore.Relational, Version=3.1.1.0, Culture=neutral, PublicKeyToken=adb9793829ddae60, processorArchitecture=MSIL">
<HintPath>..\packages\Microsoft.EntityFrameworkCore.Relational.3.1.1\lib\netstandard2.0\Microsoft.EntityFrameworkCore.Relational.dll</HintPath>
</Reference>
<Reference Include="Microsoft.EntityFrameworkCore.SqlServer, Version=3.1.1.0, Culture=neutral, PublicKeyToken=adb9793829ddae60, processorArchitecture=MSIL">
<HintPath>..\packages\Microsoft.EntityFrameworkCore.SqlServer.3.1.1\lib\netstandard2.0\Microsoft.EntityFrameworkCore.SqlServer.dll</HintPath>
</Reference>
<Reference Include="Microsoft.Extensions.Caching.Abstractions, Version=3.1.1.0, Culture=neutral, PublicKeyToken=adb9793829ddae60, processorArchitecture=MSIL">
<HintPath>..\packages\Microsoft.Extensions.Caching.Abstractions.3.1.1\lib\netstandard2.0\Microsoft.Extensions.Caching.Abstractions.dll</HintPath>
</Reference>
<Reference Include="Microsoft.Extensions.Caching.Memory, Version=3.1.1.0, Culture=neutral, PublicKeyToken=adb9793829ddae60, processorArchitecture=MSIL">
<HintPath>..\packages\Microsoft.Extensions.Caching.Memory.3.1.1\lib\netstandard2.0\Microsoft.Extensions.Caching.Memory.dll</HintPath>
</Reference>
<Reference Include="Microsoft.Extensions.Configuration, Version=3.1.1.0, Culture=neutral, PublicKeyToken=adb9793829ddae60, processorArchitecture=MSIL">
<HintPath>..\packages\Microsoft.Extensions.Configuration.3.1.1\lib\netstandard2.0\Microsoft.Extensions.Configuration.dll</HintPath>
</Reference>
<Reference Include="Microsoft.Extensions.Configuration.Abstractions, Version=3.1.1.0, Culture=neutral, PublicKeyToken=adb9793829ddae60, processorArchitecture=MSIL">
<HintPath>..\packages\Microsoft.Extensions.Configuration.Abstractions.3.1.1\lib\netstandard2.0\Microsoft.Extensions.Configuration.Abstractions.dll</HintPath>
</Reference>
<Reference Include="Microsoft.Extensions.Configuration.Binder, Version=3.1.1.0, Culture=neutral, PublicKeyToken=adb9793829ddae60, processorArchitecture=MSIL">
<HintPath>..\packages\Microsoft.Extensions.Configuration.Binder.3.1.1\lib\netstandard2.0\Microsoft.Extensions.Configuration.Binder.dll</HintPath>
</Reference>
<Reference Include="Microsoft.Extensions.DependencyInjection, Version=3.1.1.0, Culture=neutral, PublicKeyToken=adb9793829ddae60, processorArchitecture=MSIL">
<HintPath>..\packages\Microsoft.Extensions.DependencyInjection.3.1.1\lib\net461\Microsoft.Extensions.DependencyInjection.dll</HintPath>
</Reference>
<Reference Include="Microsoft.Extensions.DependencyInjection.Abstractions, Version=3.1.2.0, Culture=neutral, PublicKeyToken=adb9793829ddae60, processorArchitecture=MSIL">
<HintPath>..\packages\Microsoft.Extensions.DependencyInjection.Abstractions.3.1.2\lib\netstandard2.0\Microsoft.Extensions.DependencyInjection.Abstractions.dll</HintPath>
</Reference>
<Reference Include="Microsoft.Extensions.Logging, Version=3.1.1.0, Culture=neutral, PublicKeyToken=adb9793829ddae60, processorArchitecture=MSIL">
<HintPath>..\packages\Microsoft.Extensions.Logging.3.1.1\lib\netstandard2.0\Microsoft.Extensions.Logging.dll</HintPath>
</Reference>
<Reference Include="Microsoft.Extensions.Logging.Abstractions, Version=3.1.1.0, Culture=neutral, PublicKeyToken=adb9793829ddae60, processorArchitecture=MSIL">
<HintPath>..\packages\Microsoft.Extensions.Logging.Abstractions.3.1.1\lib\netstandard2.0\Microsoft.Extensions.Logging.Abstractions.dll</HintPath>
</Reference>
<Reference Include="Microsoft.Extensions.Logging.Configuration, Version=3.1.1.0, Culture=neutral, PublicKeyToken=adb9793829ddae60, processorArchitecture=MSIL">
<HintPath>..\packages\Microsoft.Extensions.Logging.Configuration.3.1.1\lib\netstandard2.0\Microsoft.Extensions.Logging.Configuration.dll</HintPath>
</Reference>
<Reference Include="Microsoft.Extensions.Logging.Console, Version=3.1.1.0, Culture=neutral, PublicKeyToken=adb9793829ddae60, processorArchitecture=MSIL">
<HintPath>..\packages\Microsoft.Extensions.Logging.Console.3.1.1\lib\netstandard2.0\Microsoft.Extensions.Logging.Console.dll</HintPath>
</Reference>
<Reference Include="Microsoft.Extensions.Options, Version=3.1.2.0, Culture=neutral, PublicKeyToken=adb9793829ddae60, processorArchitecture=MSIL">
<HintPath>..\packages\Microsoft.Extensions.Options.3.1.2\lib\netstandard2.0\Microsoft.Extensions.Options.dll</HintPath>
</Reference>
<Reference Include="Microsoft.Extensions.Options.ConfigurationExtensions, Version=3.1.1.0, Culture=neutral, PublicKeyToken=adb9793829ddae60, processorArchitecture=MSIL">
<HintPath>..\packages\Microsoft.Extensions.Options.ConfigurationExtensions.3.1.1\lib\netstandard2.0\Microsoft.Extensions.Options.ConfigurationExtensions.dll</HintPath>
</Reference>
<Reference Include="Microsoft.Extensions.Options.DataAnnotations, Version=3.1.2.0, Culture=neutral, PublicKeyToken=adb9793829ddae60, processorArchitecture=MSIL">
<HintPath>..\packages\Microsoft.Extensions.Options.DataAnnotations.3.1.2\lib\netstandard2.0\Microsoft.Extensions.Options.DataAnnotations.dll</HintPath>
</Reference>
<Reference Include="Microsoft.Extensions.Primitives, Version=3.1.2.0, Culture=neutral, PublicKeyToken=adb9793829ddae60, processorArchitecture=MSIL">
<HintPath>..\packages\Microsoft.Extensions.Primitives.3.1.2\lib\netstandard2.0\Microsoft.Extensions.Primitives.dll</HintPath>
</Reference>
<Reference Include="Microsoft.Identity.Client, Version=3.0.8.0, Culture=neutral, PublicKeyToken=0a613f4dd989e8ae, processorArchitecture=MSIL">
<HintPath>..\packages\Microsoft.Identity.Client.3.0.8\lib\net45\Microsoft.Identity.Client.dll</HintPath>
</Reference>
<Reference Include="System" />
<Reference Include="System.Buffers, Version=4.0.2.0, Culture=neutral, PublicKeyToken=cc7b13ffcd2ddd51, processorArchitecture=MSIL">
<HintPath>..\packages\System.Buffers.4.4.0\lib\netstandard2.0\System.Buffers.dll</HintPath>
</Reference>
<Reference Include="System.Collections.Immutable, Version=1.2.5.0, Culture=neutral, PublicKeyToken=b03f5f7f11d50a3a, processorArchitecture=MSIL">
<HintPath>..\packages\System.Collections.Immutable.1.7.0\lib\netstandard2.0\System.Collections.Immutable.dll</HintPath>
</Reference>
<Reference Include="System.ComponentModel.Annotations, Version=4.2.1.0, Culture=neutral, PublicKeyToken=b03f5f7f11d50a3a, processorArchitecture=MSIL">
<HintPath>..\packages\System.ComponentModel.Annotations.4.7.0\lib\net461\System.ComponentModel.Annotations.dll</HintPath>
</Reference>
<Reference Include="System.Core" />
<Reference Include="System.Data.Common, Version=4.1.1.0, Culture=neutral, PublicKeyToken=b03f5f7f11d50a3a, processorArchitecture=MSIL">
<HintPath>..\packages\System.Data.Common.4.3.0\lib\net451\System.Data.Common.dll</HintPath>
<Private>True</Private>
<Private>True</Private>
</Reference>
<Reference Include="System.Diagnostics.DiagnosticSource, Version=4.0.5.0, Culture=neutral, PublicKeyToken=cc7b13ffcd2ddd51, processorArchitecture=MSIL">
<HintPath>..\packages\System.Diagnostics.DiagnosticSource.4.7.0\lib\net46\System.Diagnostics.DiagnosticSource.dll</HintPath>
</Reference>
<Reference Include="System.Memory, Version=4.0.1.1, Culture=neutral, PublicKeyToken=cc7b13ffcd2ddd51, processorArchitecture=MSIL">
<HintPath>..\packages\System.Memory.4.5.3\lib\netstandard2.0\System.Memory.dll</HintPath>
</Reference>
<Reference Include="System.Numerics.Vectors, Version=4.1.3.0, Culture=neutral, PublicKeyToken=b03f5f7f11d50a3a, processorArchitecture=MSIL">
<HintPath>..\packages\System.Numerics.Vectors.4.4.0\lib\net46\System.Numerics.Vectors.dll</HintPath>
</Reference>
<Reference Include="System.Runtime.CompilerServices.Unsafe, Version=4.0.6.0, Culture=neutral, PublicKeyToken=b03f5f7f11d50a3a, processorArchitecture=MSIL">
<HintPath>..\packages\System.Runtime.CompilerServices.Unsafe.4.7.0\lib\netstandard2.0\System.Runtime.CompilerServices.Unsafe.dll</HintPath>
</Reference>
<Reference Include="System.Threading.Tasks.Extensions, Version=4.2.0.0, Culture=neutral, PublicKeyToken=cc7b13ffcd2ddd51, processorArchitecture=MSIL">
<HintPath>..\packages\System.Threading.Tasks.Extensions.4.5.2\lib\netstandard2.0\System.Threading.Tasks.Extensions.dll</HintPath>
</Reference>
<Reference Include="System.Data.DataSetExtensions" />
<Reference Include="System.Data" />
<Reference Include="System.Drawing" />
<Reference Include="System.Windows.Forms" />
<Reference Include="System.Xml" />
I tried to have a NET Core Winforms application but getting the designer working was like jumping through flaming hoops so I scratched that. It's doable but not worth the effort for my project.