Have you experimented with Meshtastic and Reticulum?

Not sure if a different comm stack other than bluetooth or WiFi would help.

I work with raw LoRa a lot and it works great.

Reticulum is pretty much a one-man-show that got a lot of press. Never saw a real network with that thing.

Meshtastic is great for communication with up to two hops. But it can become very unreliable if people use configuring wrong roles like Router/etc. in wrong position.