After quite a bit of struggle I managed to get a GNU Radio source block going for the VST analyzer part.
It's very basic at the moment, but it builds and runs.

I never really had a plan about how far to take this, so for the moment I just enjoy hating everything related, like conda, c++, pybind and a million other things that I have no (usable) knowledge about. I'm learning a lot and that's good.