> Linux is still playing catch-up on getting those usable

This is an understatement. It is completely impossible to even attempt to install Linux at all on an M3 or M4, and AFAIK there have been no public reports of any progress or anyone working on it. (Maybe there are people working on it, I don’t know).

In his talk a few days ago, one of the main Asahi developers (Sven) shared that there is someone working on M3 support. There are screenshots of an M3 machine running Linux and playing DOOM at around 31:34 here: https://media.ccc.de/v/39c3-asahi-linux-porting-linux-to-app...

Sounds like the GPU architecture changed significantly with M3. With M4 and M5, the technique for efficiently reverse-engineering drivers using a hypervisor no longer works.