I've been going down this rabbit hole myself. Already set up a solar Meshtastic node and MeshCore repeater. Kinda cool, very low bandwidth and pretty unreliable though.

It's my understanding that encryption is illegal on amateur radio bands. I'm thinking about getting a license anyways; looks fun.

HaLow, BATMAN, Reticulum and stuff like that also look cool, but I haven't messed around with those yet.

I think radio will always have bandwidth/congestion problems. It's like everyone within range is using the same "wire."

I also like overlay networks like Tor and I2P, but it's possible those will eventually be blocked or made illegal in many countries, if governments keep heading in the direction they seem to be heading.