I took a plunge into learning about mesh networks, specifically because I love the idea of p2p/decentralized systems of communication. To be honest, I was surprised to find that my expectations for “where we are at” with this type of technology was pretty off-base. For some reason I thought by now it would be straightforward to do a little more than text messaging over a truly public and decentralized off-internet mesh. Maybe I’ve missed some things in my search (still learning!) and someone can correct my understanding.
You can create a network tunnel over meshtastic with the CLI. I haven't had the time to try it but I assume it's quite slow.
The Reticulum Network Stack is a more generic lora capable protocol. It is intended to run over almost any two way link so it's less bandwidth efficient per packet than Meshtastic but in return it gives you packet routing rather than flooding. It can be run over TCP, LoRa, WiFi, etc.
https://reticulum.network/start.html has an overview and how to connect.
There is a manual with a lot more information on how it works and the ideas behind it at https://reticulum.network/manual/ however it's quite large and not really a user friendly guide
If you just want to play with it https://reticulum.network/manual/software.html has a list of clients and software using it.