As a thought experiment, what would happen if you wrote your own malicious payload to a burner device and handed that over? What if you warned the border agents that your device would deliver malicious code and they plugged it in anyway?
edit: It was the Signal founder. https://appleinsider.com/articles/21/04/21/signal-hacks-cell...
But I would just format it.
plausible deniability.
edit: please dont actually do this.
You're describing a (digital) booby trap. Since you're knowingly targeting law enforcement officers, I'm not sure legal theory factors into whether you could get away with it in practice but even theoretically the answer is probably no, that's a computer crime.