How Apple silicon Macs create LocalPolicy to allow another boot volume group to be used, the problems that can occur, and how to investigate them.
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To understand what might go wrong when trying to boot an Apple silicon Mac from an external disk, start with LocalPolicy: what it is, and how it works.
Why can some with Apple silicon Macs create and boot from external disks, while others seem doomed to failure?
Monterey changes the way that Recovery works on M1 Macs, making them more like Intel Macs by using a paired Recovery volume. But that could spell trouble.
One command, bless, used to do it all, copying boot.efi to the right place and declaring the volume bootable in its header. Where are we with Big Sur and M1 Macs?
One command in Terminal which instantly disables any support, and why you can’t (yet) boot your M1 Mac in Linux.
How changing a volume’s boot policy can let you boot in older macOS, and update, if you wish. For anyone who uses external bootable disks with an M1 Mac.
Unlike Intel Macs, M1 models always start booting from internal SSD, and can only offer full Recovery from there too. This has benefits, and some drawbacks too.
The Eclectic Light Company 