There's aren't really any alternative OS [1], but I don't think it's fair to say there's a closed software ecosystem. You can install/compile/run whatever you want, including kernel extensions. The hardware isn't locked.
[1] Hardware isn't locked: https://asahilinux.org/about/
> Apple allows booting unsigned/custom kernels on Apple Silicon Macs without a jailbreak! This isn’t a hack or an omission, but an actual feature that Apple built into these devices.
They don’t provide any source code or documentation (which they easily could) so if want to do literally anything with your “open” device you must first reverse engineer the entire MacOS driver stack like the Asahi project did. Great fun, but it’s a criminal waste of incredibly talented engineer hours.
On top of that, the reason Asahi doesn’t work on M4 and later is that Apple has intentionally modified the ARM core to prevent stock MacOS from running once the hardware is “unlocked,” which makes it way more difficult to reverse engineer.
Bastards.
Naturally, the benefit for Linux is still the variety available in distributions. While IBM's RHEL and Canonical's Ubuntu may adopt some questionable stuff, Slackware, Devuan, Omarchy, and such likely won't.
Can you elaborate at all?
The performance you get with M5/M6 in theory is crazy (especially having matmul cores with such an energy envelope and unified memory). By the time I can use it well in Linux there will be M7/M8 though.
With NVIDIA I can buy a Blackwell based core right now and use it (even if I will have much less GPU memory. Though it will be high bandwidth).