Someone recently posted asking if we had a Matrix room. I used to be opposed to hosting one because moderation can be a bit difficult. The recent Discord issues have shown more interest in Matrix lately so I guess it's worth experimenting on.
You can join the room #general:ani.social using any existing Matrix account if you already have one. But if you would like to make a new account on the server, you can DM me for a registration code. The room is public so anyone can join.
The server uses Matrix Dendrite which means that there may be some Matrix features that are not available yet.
Yep, Tuwunel or Continuwuity seem to be the only reasonable alternatives to Synapse right now. Both are forks of Conduwuit. Tuwunel is the one that was marked by Conduwuit's author as THE continuation of Conduwuit, and it has some corporate backing. But apparently Tuwunel's maintainer is a jerk, and after your standard open-source drama community gathered around Continuwuity instead, and it's the latter that seems to be recommended everywhere whenever someone asks for a Synapse alternative. Anyway, either of them would be a better choice than dendrite at this point.