While potentially great idea for local area communication, I'd very much prefer more work on basic UX and usability for now.
As for non-local communication, I'm not sure how well that fits with SimpleX model. Briar is able to use mesh of relays that can be only intermittently connected to each other. On the other hand SimpleX is designed to give as little information to relay nodes on the internet about the origin or recipient of the messages. From what I'd read of it so far I'd assume that giving relays enough information to route messages to you would be counter to it's privacy guarantees.