Maybe run the ‘full stack’ for XMPP servers on raspberry pi zeros and use Meshtastic to link the individual servers using the MQTT features recently added.
What would be really cool is what was mentioned before, a PWA (Progressive Web App) that has a richer chat interface / features and allows more than one user / identity to natively use a node over wifi.
Something that should be easily possible for a single connected user per node.
I have not been able to follow as closely as I use to as of late but from what I remember the underlying layers assume there is only one users per node / phone. I’m not sure if that was changed in the 1.2 branch but I do distinctly remember it being discussed as a bit of a limitation a long time ago.
What would be really ground breaking, but a big stretch for the project right now is integration with Secure Scuttlebutt - Wikipedia Meshtastic <--> Secure Scuttlebutt