I like simple x but whats wrong with signal ?
We need to start transitioning from signal, telegram to nostr:npub1exv22uulqnmlluszc4yk92jhs2e5ajcs6mu3t00a6avzjcalj9csm7d828 
Discussion
You need a phone number to use it
Sgt Fish- it's The Phone number. Which might create a connection graph somehow between others and you, groups of associated people.
SimpleX has a specific feature to eliminate that data point. I forget it's name. It was pretty interesting to read through their change logs from version 2 up to version 5.