Access O365 Modern Groups information from VSTO Outlook Add-in

I want to build an add-in for the MS Outlook 2019 desktop app (-> VSTO add-in). It is intended to gather some information from O365 Modern Groups that the current Outlook user (me) is a member of. As far as I understand the only way to achieve this is to use Microsoft Graph API because there is no support to access O365 related things via Outlook object model/Office Interop. Given that (and please correct me if I am wrong) I might use the Microsoft.Graph Nuget packages. With them I would like to call the following endpoint:

POST /users/{id | userPrincipalName}/getMemberGroups

possible in C# with this code snippet:

GraphServiceClient graphClient = new GraphServiceClient(authProvider);

var securityEnabledOnly = true;

await graphClient.Me
    .GetMemberGroups(securityEnabledOnly)
    .Request()
    .PostAsync();

My question is: Is there a way of using the existing Outlook credentials for the authProvider so that I don't need the user to enter credentials? I read that web add-ins have the possibility to use different authentication flows including a SSO flow. But that does not fit for VSTO.

I thought of a IntegratedWindowsAuthenticationProvider. But therefore I need to provide a clientId which I do not have. Does that ultimately mean that I need to register my add-in in some way? Can't I just write an add-in for my personal purposes without admin support?

IPublicClientApplication publicClientApplication = PublicClientApplicationBuilder
            .Create(clientId)
            .WithTenantId(tenantID)
            .Build();

IntegratedWindowsAuthenticationProvider authProvider = new IntegratedWindowsAuthenticationProvider(publicClientApplication, scopes);