That's even sexier! I was looking into private cell radios a while back, and while it seemed possible the cost was prohibitive!
Why is nobody talking about open source LTE or 5g? There are several actively developed open source 5g stacks. https://open5gs.org/
and https://free5gc.org/ are just a couple of examples.
Discussion
With LTE and beyond most of the infrastructure is software (for which there is open source). For $1000 you can buy an eNodeB which is the only piece of backend hardware needed for phones to connect to. On android you can pick the mobile network like you choose WiFi.
Please teach me more XD
The issue I found was there was no readily available (or open) hardware that adapted to standard networking like 802.11. Id want to be able to make a big wifi radio if that makes sense. I wasn't able to find any options like that? The closet things I found required a lease from the mfg.
Maybe it has no hobby community due to thinking that it is owned by the corporate realm. That may be true for SIP (voice/SMS) but beyond that anybody can run it and I don't see why there can't be a robust grass-roots data-only network. I don't know much but maybe will start looking at it more and can start something on nostr.
Until recently I had my own voip network and pbx with desktop/landline phones because I'm a nerd.