Is radio like LoRa actually usable for useful things like file transfer, or is it more like a toy?

meshtastic plans to support more radios then only LoRa so worth updating,

so for example you can use esp32 lora node not only for lora low bandwidth comms but also high speed wifi transfers, for example pictures of intruders !

no just joking.

I don't understand how this is different from Meshtastic. Can someone compare and contrast?

Really excited about all the new mesh networking protocols being worked on. As mentioned in the repo, also check out Meshtastic and Reticulum.

Would love to see something like this for Bluetooth/wifi. Maybe Wifi Aware will be that.

I think local-first networking is going to be an important part of local-first apps.