>  so we could not hop on WiFi and message each other using Signal.

I have a feature request for this actually. I think if it got a harder push they would consider it. It's not full decentralization but does still prevent the concerns that Moxie and Meredith have stated.

It is like you say: I too wish Signal would allow for communication over any available medium.

https://community.signalusers.org/t/signal-airdrop/37402