I think we're just a few steps away from having our own devices in such a deeply locked state that boot disks will eventually stop working on any sufficiently modern system.
They aren't going to backtrack on all that. That'd be silly.
So please stop the FUD about Apple locking their devices down; this is a Mac, not an iPhone :-)
Has nothing to do with trying to impose additional restrictions.
For now, maybe. Consider the time when microsoft was partially successful to boot-lock arm devices: https://www.softwarefreedom.org/blog/2012/jan/12/microsoft-c...
The old adage "do not assign to malice what can be properly explained by stupidity" should not be blindly applied when it involves powerful companies.
Bugs are being worked out slowly, and there's no reason to assume bad intentions here. (I have an Apple M1 MacBook Air, and it boots from a Samsung T7 external SSD just fine)
Though ARM appears to be missing an open-spec BIOS/Boot standard like x86 has.
It's just the embedded junk (which includes Apple) that doesn't care. Apple has vertical integration, they only care about the full experience including their own OS. Embedded SoC vendors only care about having some "BSP" fork of Linux because that is enough to make a crappy device with it. There's just, unfortunately, zero motivation for these vendors to embrace standards.