The people behind Plan 9 did a much better job than was done with X11 and that was completely ignored as a path forward from what I can tell.
It’s tiny, secure, graphics subsystem independent (it’ll work on just about anything with or without a GPU, I would expect, given the API is so damn simple) and already designed.
Maybe it wouldn’t work, but I bet it would have.
Everything is a file doesn't play well with how GPUs work, especially modern ones.
Plan 9 and later Inferno, just had plain 2D rendering.