I just found this recent article on Macworld, *
How to start up your M1 or M2 Mac from an external drive*
https://www.macworld.com/article/331...nal-drive.html. He says it can be done. I*m loathe to try it myself (not lazy, but I don*t have time to spare on what might ultimately be futile, and I don*t want to risk messing up my external drive which is partitioned for a clone + Time Machine) until you, Dave (who may have an M2 Mac by now), tests this and reports your results.