Just stumpled upon this new #DID method, and I think this has a chance of working, because it's based on the Mainline DHT that BIttorrent uses:
https://did-dht.com
To keep IDs available when your devices are offline, you publish them to gateway nodes who may or may not charge for that service. (Or run your own, of course.)
Gregory's Server
To keep IDs available when your devices are offline, you publish them to gateway nodes who may or may not charge for that service. (Or run your own, of course.)