The key words are "optimized" and "OpenGL 4.6 with Zink". "Functional" and "OpenGL 2.1" is a different story, and the same trustworthy source said in https://rosenzweig.io/blog/asahi-gpu-part-6.html that:
> thanks to the tremendous shared code in Mesa, a basic OpenGL driver is doable by a single person. I’m optimistic that we’ll have native OpenGL 2.1 in Asahi Linux by the end of the year.
It's likely that even a bare-bones OpenGL driver will probably run better than llvmpipe, which is especially important in a laptop context due to the resulting power use improvements.
> thanks to the tremendous shared code in Mesa, a basic OpenGL driver is doable by a single person. I’m optimistic that we’ll have native OpenGL 2.1 in Asahi Linux by the end of the year.
It's likely that even a bare-bones OpenGL driver will probably run better than llvmpipe, which is especially important in a laptop context due to the resulting power use improvements.