Ultimately they build command buffers and send them to the GPU. You'd need a way to do that from macOS. The original Mesa drivers for the M1 GPU were bootstrap

Ultimately they build command buffers and send them to the GPU. You'd need a way to do that from macOS. The original Mesa drivers for the M1 GPU were bootstrapped by doing just that, sending command buffers to the AGX driver in macOS using IOKit. https://rosenzweig.io/blog/asahi-gpu-part-2.html https://rosenzweig.io/blog/asahi-gpu-part-2.html https://github.com/AsahiLinux/gpu/blob/main/demo/iokit.c https://github.com/AsahiLinux/gpu/blob/main/demo/iokit.c So you'd need a bit more glue in Mesa to get the surfaces from the GPU into something you can composite onto the screen in macOS.