The new DECT NR+, the first non-cellular 5G standard supports mesh configuration but fixed not mobile network:

DECT NR+: A technical dive into non-cellular 5G:

https://devzone.nordicsemi.com/nordic/nordic-blog/b/blog/pos...

I wonder if ESP-NOW[0] would be useful for this. I've been toying with building some mesh-based lighting controllers for synchronizing lights. Fortunately it can be entirely static (number of nodes) which makes it an easier problem than dynamic meshes.

0: https://www.espressif.com/en/solutions/low-power-solutions/e...

Correct. Source: I do low-energy mesh networks. There are loads of tradeoffs, and a lot of it just has to do with the physical medium.

Sure, you could go with an off-the-shelf solution, but those aren't always a good fit for whatever product you're developing. If you can squeeze your bandwidth requirements to an absolute minimum, say, tens of kilobits, you can accomplish absolutely nutty stuff with a cheap LoRa radio and a well-designed antenna. Sure, it's tens of kilobits, but it's tens of kilobits sent and received over a mile between devices with batteries the size of your pinky.

Mesh networks are a neat idea, but the reality of is often disappointing e.g. given compatible radios all the IoT devices in a room could form a mesh network of equal peers, but if a few lightbulbs use their position (mains powered, good location) to form a hierarchical network it will actually work (without wasting battery power and air time).