For a while, there was a community of stations creating an infrastructure similar to the dial-up BBS world, including message forwarding (UUCP).
There were even a few Internet gateways for a while. (I ran one of the two that were reachable from my corner of LA.) I imagine they're everywhere today.
(Getting married and raising children can quash a lot of hobbies.)
When I had time, I had no money for equipment. Now that I have money and knowledge, no time…
TNC is "terminal node controller". They're kinda sorta like modems for radios. KISS TNC is a particular protocol for communication between a radio and a TNC.