generic interface within delegate at startup class

Using .Net6 Azure function I am trying to refactor out an existing set of logic to return an object of type T vs the current void. The current solution is first with my attempt below:

CURRENT

The current closed IHandler code/implementation is

IHandler.cs
{
    Task HandleAsync(IMessage message, CancellationToken cancellationToken);
}

and in program.cs

services.AddScoped<Func<MessageType, IHandler>>(sp =>
    dataType =>
    {
        switch (dataType)
        {
            case MessageType.HandleA:
                return sp.GetService<HandleA>();

            case MessageType.HandleB:
                return sp.GetService<HandleB>();

Implementation

public class HandleA: IHandler
{
    public async HandleAsync(IMessage message, CancellationToken cancellationToken)
    { ... //do work in here
    }
}

PROPOSED ATTEMPT

The Problem: What I would like to do is create a handler that returns a generic object but the delegate in program is messing with my head. Current (not compiling, but can't see way out)

public interface ISvcMessageHandler<T> : IHandler where T : class
{
    Task<List<T>> ReturnObject(IMessage message, CancellationToken cancellationToken);
}

program.cs The issue here is that I have to strongly declare T with a concrete class

//obviously T is not known here. 
services.AddScoped<Func<MessageType, ISvcMessageHandler<T>>>(sp =>
    dataType =>
    {
        switch (dataType)
        {
            case MessageType.HandleA:
                return sp.GetService<HandleA<DtoA>>();

            case MessageType.HandleB:
                return sp.GetService<HandleB<DtoB>>();

Implementation

public class HandleA: ISvcMessageHandler<DtoA>
{
    public async Task<List<DtoA>> ReturnObject(IMessage message, CancellationToken cancellationToken)
    {
        ....do work
        return foo;
    }
}