#linuxmint 's Hypnotix still uses X11 (or XWayland).
Why?
Because it's using libmpv vo=x11 hack for embedding.
See https://github.com/jaseg/python-mpv (Hypnotix uses it) for details.
Possible alternatives?
Hacks like "render context" - example (yes its #qt , #gtk has its own opengl thing) https://github.com/feeluown/FeelUOwn/blob/25a0a714b39a0a8e12cd09dd9b7c92bf3c75667c/feeluown/gui/widgets/mpv.py
However it's laggy on low-end computers (yes i've tried it).
What's easier? vo=x11 or trying to mess with OpenGL or ditching mpv (most stable video player on Linux btw) for who knows what? You decide.