By requiring signed firmware and holding the signing keys.

Even if this was overcome (checkra1n) or they provided for bootloader unlocks to run an unsigned firmware, you would still then need to reverse engineer all the drivers. It’s why you don’t see stuff like the original iphone SE’s running different OS.

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gbear605 7 hours ago | parent [-]

It would be difficult, but it would at least be possible. See projects like Asahi Linux where they did the work to reverse engineer the drivers for ARM-based Macs.

	▲	grishka an hour ago \| parent [-]
		And I'm sure a lot of that work could be reused for the A-series SoCs.