Debugging a Dynamics365 code activity locally

I have a Dynamics365 (in the cloud) setup and I am tasked with debugging some of its custom workflow activities that are suspected of not working properly. As a long-time desktop developer, this whole cloud setup makes it very tricky to do any decent debugging.....

So my code activities all look something like this:

public class MyCustomActivity : CodeActivity
{
    public IOrganizationService OrganizationService { get; private set; }
    public IExecutionContext ExecutionContext { get; private set; }
    public CodeActivityContext ActivityContext { get; private set; }
    public ITracingService TracingService { get; private set; }

    // Bunch of input parameters
    [Input("param1")]
    public InArgument<string> Param1 { get; set; }

    [Input("param2")]
    public InArgument<string> Param2 { get; set; }

    // possibly output parameters
    
    // main method with all the logic
    protected override void Execute(CodeActivityContext context)
    {
        var serviceFactory = context.GetExtension<IOrganizationServiceFactory>();

        this.ActivityContext = context;
        this.ExecutionContext = context.GetExtension<IExecutionContext>();
        this.OrganizationService = serviceFactory.CreateOrganizationService(ExecutionContext.UserId);
        this.TracingService = context.GetExtension<ITracingService>();

        // actual core of the code activity
    }
}

Very basic, run-of-the-mill code for a Dynamics code activity, I believe.

I was wondering if there's a way (without moving heaven and hell) to create a custom (not really "faked") CodeActivityContext so that I could basically write a little "test app" that would create such a context, instantiate the code activity, and then run its Execute method? This would allow me to actually run and debug the test app, and go through it and see what's going on (and what might be going wrong).

I am aware of the Fake Xrm Easy package by Jordi Montana and have used it in my integration testing (wonderful piece of code!) - but I think that won't really work for me in this scenario, since I need the "real thing" - I need to have a working IOrganisationService primarily, to run the code activity's code and see what it's doing with the Dynamics platform...

Any ideas? Has anyone else attempted to do something like this before??