@zleap @cmthiede @gimulnautti @davetroy ActivityPub is designed for http/https style traffic with service servers being maintained by someone that are out on the web with a public IP. When one goes down or you want to move you have to do a re-homing (it's baked into the protocol I think).
But, if you just wanted to share stuff with friends you could do it over I2P or Tor and that has a unique address that is a key.
One part of the idea bouncing in my head. Detach from the web.