Disclaimer: I not a security expert by any means. Also I am NOT from a country "where such concerns are very common".

So I feel like I am missing something here.

I don't want to minimise empathy towards living under such a society but if The Adversary can obtain your friends unlocked phone, what do you want to have happen?

A sham-password for Signal that sends out a "I've been caught." message to all contacts? So you can "fat finger" the password in front of your captor?