If you are interesting enough, Signal doesn't help at all. Some nation state will have NSO infect your mobile device with Pegasus and record everything you type, say and do.

People need to understand this. There is no solution for mobile device compromise other than to stop using these devices.

And if you cannot stop using them, then you must understand that everything you type, say and do on or around your mobile device is (or will be) public. So treat it like a public device at all times.