Comment by sneak

This is a false statement. Intel macs have the T2 boot security chip, which requires online activation to be able to access the internal disk after a full system wipe. The M1, even in reduced security mode, also requires online activation after a full system wipe. I've tested this this week; if you know of something I'm missing please tell me the exact steps to take to wipe and reinstall a T2/M1 mac offline, as I am confident now that it is not possible to do so.

I would love to be wrong about this.

This is the case even if you have a full offline boot/restore USB.

I have a post coming out today about just this, and how it renders all current macs unsuitable for long term offline/airgap applications.