M-series Macs require a functioning internal drive in order to boot off external storage: https://tidbits.com/2021/05/27/an-m1-mac-cant-boot-from-an-external-dr

M-series Macs require a functioning internal drive in order to boot off external storage: https://tidbits.com/2021/05/27/an-m1-mac-cant-boot-from-an-external-drive-if-its-internal-drive-is-dead/ https://tidbits.com/2021/05/27/an-m1-mac-cant-boot-from-an-e...