> Nobody decided that it's a crime, and it's unlikely to happen.

Which jurisdiction are you on about? [1] Pick your poison.

For example, UK has a law forcing suspects to cooperate. This law has been used to convict suspects who weren't cooperating.

NL does not, but police can use force to have a suspect unlock a device using finger or face.

[1] https://en.wikipedia.org/wiki/Key_disclosure_law

I gave you the answer that exists: I'm not aware of any existing or likely-to-exist secure messaging solution that would be a viable recommendation.

The available open-source options come nowhere close to the messaging security that Signal/Whatsapp provide. So you're left with either "find a way to access Signal after they pull out of whatever region has criminalized them operating with a backdoor on comms" or "pick any option that doesn't actually have strong messaging security".

You're asking for a technical solution to a political problem.

The answer is not to live with it, but become politically active to try to support your principles. No software can save you from an authoritarian government - you can let that fantasy die.

This may shock you, but plenty of cutting-edge application security analysis doesn't start with source code.

There are many reasons, but one of them is that for the overwhelming majority of humans on the planet, their apps aren't being compiled from source on their device. So since you have to account for the fact that the app in the App Store may not be what's in some git repo, you may as well just start with the compiled/distributed app.