The latest release is dated 2 days ago https://github.com/markqvist/Reticulum . Actively supporting is not the same as actively developing.

This should probably be taken as “I am tired of supporting everyone who did not RTFM, too bad if you can’t make it work” and is a totally reasonable thing to do, especially as the project gain more traction.

There is a pretty good community around reticulum that is usually supportive.

The reticulum project with the Sideband client is probably a lot more censorship resistant than DeltaChat or Meshtastic.

This is not what you asked for specifically but check out tqm https://github.com/autobrr/tqm it does everything you want automatically. It takes a bit of fine tuning but it can handle a lot of scenarios.

The two options I know of are Headscale and Netbird.

To answer the last part of your post:

So far my experience is that the RCS-iMessage feature is working (or not) depending on the Apple user’s provider. I’m on Android with a “cheap” provider in Canada and RCS-iMessage work with my iMessage contacts that are on major providers but those on cheaper providers don’t work yet.

So if you are on Android and your basic RCS works you should be good.