Talked about pyenv bug here: The current state and the future of Python on Haiku
It is / was a problem with some libraries.
Be/Haiku Backend for GTK is the way to go, but i didnt really understand much of the Broadway code itself (was designed to be server<->client implementation), but other peeps may do. Fortunately, “you” can test it after doing the port, just running a GTK example from the build process itself.