This article came up https://www.vice.com/en/article/v7e9y3/activists-are-designing-mesh-networks-to-deploy-during-civil-unrest
about an open source mesh network (including the hardware made from easily accessible parts) to be used when governments shut down the internet. It seems the original project is dead, but I did manage to find this repo https://0xacab.org/kirsa/mycelium-mesh-old/
I have (as of this moment) limited expertise in hardware and protocol programming but I have time and resources to delve into it and perhaps start it back up.
There's several things they mention in the description of the program, such as a lack of encryption, lack of peer to peer, how all messages are saved in nodes, etc. These strike me as someone with not too much knowhow, as bad design aspects.
I would like to dedicate this thread to trying to dig up more info on this project, and for people with more know how to chime in on what ought to be different, if you would restart as the sole dev(s) anyway, or pointers on where to start.