Signal the Protocol is good, & these are good adaptations of it.

#SimpleX is what I recommend most typically among my circle.  The basic idea of "2 relays, 1 per side, instead of one signal dot com for both sides of the chat" is a really easy no-cost privacy-win concept to communicate to technotypicals 🙂 

 Awesome I haven't heard of oxchat or nextcloud talk.. thanks for that.