I'm not sure what the problem with the android version of Element X might be, it works perfectly for me and my wife. Voice and vid work fine, but that's also using the matrix.org server. YMMV with your own self-hosted server, I have one for my agents but I haven't used voice/vid with it.
And yah, I had high hopes for NC Talk, but it's not worth the trouble even if you provision a STUN/TURN server.