[lhamil64]

Have you seen Meshtastic (https://meshtastic.org/)? It seems like a similar concept but using dedicated devices and unlicensed ISM frequencies, and it's a proper mesh network (so you can even setup repeaters to provide better coverage for an area). I guess they wouldn't work too well if you're travelling to another country since you'd have to get the right radios for the country but it's a neat idea.

[myself248]

Furthermore, the latest build of Meshtastic mentioned some LAN networking, so nodes that don't have radios can still exchange messages if they're connected by some other means.

That seems just a hop skip and a jump from having a Bluetooth WPAN/WLAN that lets many phones share one or zero Meshtastic radios but still be able to talk to each other...

[brokenmachine]

I've been checking out https://reticulum.network/ which does the same thing as meshtastic, but encrypted. Looks like it's in the early stages though.