I was JUST working on this based on the solarpunk forum article that was on Hackaday, yesterday.
I was trying to do Enigma with a captive portal wifi setup and a (heavily stylized) terminal in a browser. Figured a pi zero w2 might do the job on solar.
The idea was occasional fidonet pickup, some door games, and probably disabled file base. I could seed a few on friends and family porches in the neighborhood, and just see if anyone uses them.
It (enigma) was proving to be a real pain though, and I decided to shelve it for a bit.
Reticulum/Rnode is one option, but then mesh-core-tastic, signal, session, simplex, briar, whatschat, insta-don't sell a gram (no more e2ee) etc. etc. Let me know when the cool kids figure it out, you can reach me on my fossil instance over i2p :D
The early dialup and BBS world was magic and it pulls everything completely off of the standard channels.