alt Hacker NewsXMPP is a no go, sorry. There's just no good iOS app (or Android, I think). And you can't come back and say some app you love is feature complete, or whatever. It has to LOOK good.
Matrix will work though. Element X is very polished. Same with FluffyChat. However, I still only bother with getting my immediate household to use it. A "family" chat is totally fine with me. And that let's me hook bots and agents up to it.
For a little plug... it's can very easy, in fact, to get a Matrix server set up these days, including full voice and video chat: