Of course, this is a kill switch, but that's usually detectable if the attacker is sophisticated enough. Plus, they can always backup the disk before.

Plausible deniability lets you pretend you do not have incriminating data, but it's tricky to use in the first place: https://gitlab.com/cryptsetup/cryptsetup/-/wikis/FrequentlyA...

Travelling with an empty disk seems like a more appropriate option. Dm-verity could probably be used to check that there has been no tampering.

In software, where there's a will, there's a way.

Darknet Diaries has a cool episode about the dark cellphone industry: https://darknetdiaries.com/episode/105/

Of course, but this won’t be easy with commodity hardware. Standard practice is to use write-blockers to prevent this kind of tricks, but of course you can prevent write-blockers by integrating your storage.

I think you could get a pixel phone to do this in a useful way.

Lookup "duress passwords"

* https://en.wikipedia.org/wiki/Duress_code

The feature is more relevant in (full disk) encryption software than OSes.