Last time I onboarded a Mac (a few months ago), it would very explicitly ask if you want to enable support for remote FileVault unlocking.

That said, they could also roll out a small patch to a specific device to extract the keys. When you really want to be safe (and since you can be a called a 'left extremist' for moving your car out of the way, that now includes a lot of people), probably use Linux with LUKS.