Meshtastic should be the obvious answer for this but in my limited experience the app(s) and code are buggy on even the most typical hardware. Wish it wasn’t the case but it is.
If you're talking about a few miles/KMs between nodes, plain old LoRaWAN might be more than sufficient, esp. for the sensor use case. The nice thing about using LoRaWAN is that's it's literally providing an IPv6 overlay so you can run e.g. MQTT or a text-based messaging protocol designed for regular TCP/IP use. UDP is preferable to avoid frequent session resets and keepalive traffic chewing up your available bandwidth.
Meshtastic and MeshCore can theoretically provide "infinite" range so long as there are peers between the nodes you want to connect. Theoretically, mobile peers can also serve as store-and-forward nodes so that reachability doesn't need to be constant, just frequent enough to handle the messaging you want to do.
I would absolutely not rely on either for a safety-critical application, though. If you want emergency comms in case something happens while you're out on the mountain, use a satellite communicator. There are a ton of these marketed for outdoor/portable use, and they have much more robust "SOS" capabilities (up to and including direct dispatch of search-and-rescue).
Of course, for real emergencies I have a Garmin SOS device. It would just be "nice" to have something for local 2-5 km communication that doesn't need a clear view of sky, works partially underground, etc. GMRS is "fine" but from a physics perspective a digital signal with Chirp encoding should go further and be more reliable.
Seems like JS8Call or Packet radio might more in line with what I want. It's just surprising that something like Meshtastic hasn't replaced them.
> Of course, for real emergencies I have a Garmin SOS device.
that's why the mesh radio/LoRaWAN-type ecosystems suck. I don't mean to be rude or snarky; just to point out a very contextually-relevant example against your argument.
For the average consumer who needs this functionality seriously, there's a proprietary (and often costly) solution. Subtract those mission-critical-remote-comms devices and you're left with hobbyist needs, so you get hobbyist-quality ecosystems.
From what I recall, meshcore de duplication only tracks like the last 256 messages so that could quickly fail to de duplicate.
I think people need to think more about what the actual scenario they have in mind is because it seems most people think of mesh radio as some backup for the government shutting the internet down. When in reality it’s almost useless for that since it’s so easy to jam or flood mesh radio.
Not LORA.