[eddyb]

If your Linux distribution is handling Mesa packages correctly, you will never lack OpenGL/Vulkan drivers.

The reason is that Mesa includes "software rendering" drivers for both OpenGL ("llvmpipe") and Vulkan ("lavapipe"). As the name(s) might suggest, they use LLVM to JIT shaders for your CPU (supporting SIMD up to AVX2, last I checked - although typical compositing shaders tend to get pattern-matched and replaced with plain `memcpy`s etc.).

So you should always be able to run a fully-featured Wayland desktop (albeit limited in performance by your CPU), on any unaccelerated framebuffer, nowadays (and I remember doing this even before Plasma 6 launched, it may be older than usable Wayland desktops tbh - the Mesa code sure is, but maybe distros hadn't always built those drivers?).

[ahartmetz]

Software OpenGL rendering technically works, but is IME unusably slow for compositing. What does work okay is direct software rendering. It might work to configure OpenGL to hit all the fast paths in the software backend (which you might need to add first), but I'm really not sure if you can do it without at least some unnecessary data copying.

[vrighter]

you missed the "3d accelerated" part.