Isn't Renpy's codebase pretty divorced from pygame these days?
I don't think divorced is the right word. Ren'Py is built on top of Pygame, to the point where there are several places where Pygame's API is incorporated into Ren'Py's. (For example, creator-made GUI widgets are expected to handle pygame events, and Ren'Py's drawing canvas support is a thin wrapper around pygame.draw.) Ren'Py also uses Pygame services where suitable - all image loading goes through Pygame, and Ren'Py makes extensive use of Surfaces internally.
At the same time, there are several modules that Ren'Py has its own implementations of. Like many games, Ren'Py uses OpenGL (as well as OpenGL ES and ANGLE) for graphics rendering. It has its own libav-based music and movie playback system, so it can play multiple sounds at the same time, and a range of movie formats. Finally, it has its own text rendering module, which seemed necessary to deal with text-heavy games.Â
I'll claim that Ren'Py is still based on pygame - but I'm willing to bypass it when necessary.Â