I am also interested in such a feature of TH. It is not one of my burning issues, but reading this post I thought one could pool together.

I'd like to use TH to find what classes a type is an instance of, or alternatively all known instances of a class.

In particular I am additionally interested in accessing the class functions via an instance of that particular class.

As far as I can tell this is not yet possible.

This confirms my conjecture, too.

How hard would it be to implement? I'd like to help out, but it would be nice to have some idea of where to start. Any tips?

Unfortunately, I don't have a clue either. Greetings, Martin