A rendering engine and a UI library are totally different; there’s no reason one should include the other. There are rendering engines for Python, as are UIs. The trick is finding a pair that’s compatible.
Pygame is a rendering library, and there have been UI libraries implemented atop of it: https://www.pygame.org/wiki/gui.
I’m very much a DIY kind of person, and since I was already making my own rendering engine, I ended up implementing my own UI as well. It took up some time, but in the end I have something that works for me. That’s always another option for you.