You can do it but even an event with a short content property is going to be a few hundred bytes. On lora this will take a while to broadcast and isn't very civil. I've done it with a Lora mesh network on esp32 devices broadcasting a Bitcoin tx from 10k with no internet. It works but not sure it's practical. A better approach where you don't need each device to sign the message would be to broadcast the message to the mesh in cleartext and an internet connected node, constructs, signs the event and published to relays. One possible approach.