@marc0janssen
I think you need to set up first your threat model. Do you need your chats to be secure while you chat with your friends? Or do you need to have anonymity while chatting? I don't need anonymity but I like my chats to be secure with FOSS project so I'm using Signal which is proven to do that job very well. https://thehackernews.com/2016/10/signal-messenger-fbi-subpoena.html?m=1
As for anonymous chat apps I suggest Briar, but again you have to scan each other QR codes for identity exchange
@resist1984