Ham radio is a thing but it's at best dialup speed and not a wide band available. I would suspect digital signals are allowed in some parts of CB band which is your VHF/UHF and good for scores of kilometers of range, with enough bandwidth to carry, well, in the old 12 or so channel VHF of the pre-digital, now carries about 100 channels.

In theory there might be "legal" frequencies that you can set up long range low bandwidth shtf connections, and worst case you can just build the tranceivers anyway and use waveguides to reduce the chance of the signal being picked up by FCC or nutters who literally spend all their time listening to scanners.

There really needs to be more work on this. Like, there is loads of routers out there that just need some extra parts and you can turn them into wifi line of sight connections maybe up to a kilometer range if you are lucky, per hop, hard part is placing them where no do gooder is gonna interfere with your gear. There's a shitcoin project that involves running these things in low coverage areas. Wifi bands are entirely free, and if you can get good antennas and hide them well it would be the citadel uplink for sure.

And there is bitcoin satellites, thanks to Blockstream. I expect this will continue to develop until you can literally read and write to the chain from anywhere in the world with a little satellite modem.