I don't see a bug opened for it so I'm gonna write one to track the progress. Mesa has the ability to work with Apple Silicon's GPUs thanks to Alyssa and AsahiLina so I'm going to ask when it will added to our ebuilds. Chadmed already posted an ebuild on his overlay [1] with it enabled and I can confirm it works, at least on M1. I've asked to him to push changes on gentoo's recovery and waiting for a response. [1] https://github.com/chadmed/asahi-overlay/blob/f860e025b1df07b79b699328b6a6f0bcdfc91dd3/media-libs/mesa/mesa-22.2.0-r1.ebuild
As we discussed on IRC, we don't want to do this right now because it requires unmerged changes to kernel.