I managed to get extended family onto Discord. Also have one just for my non-extended family. It works great.

Signal has stuck for a couple of friends, but has decidedly not stuck for anyone else - and the ones it stuck for were either already on it or have a privacy bent.

Signal, back then at least, didn't do group chats, or nowhere near as conveniently as Discord. So much so that I don't even know if Signal does group chats now as I only ever use it for one-on-one.

I set up a Matrix server back then too, didn't take. Discord won.