Can one use this combined with a HTTPS actor? e.g.
{ "@context": [ "https://www.w3.org/ns/activitystreams", "https://w3id.org/security/data-integrity/v1", "https://w3id.org/fep/ef61" ], "type": "Note", "id": "ap://did:key:z6MkrJVnaZkeFzdQyMZu1cgjg7k1pZZ6pvBQ7XJPt4swbTQ2/objects/dc505858-08ec-4a80-81dd-e6670fd8c55f", "attributedTo": "http://host.example/actor", "content": "Hello!", "to": [ "http://host.example/followers", "https://www.w3.org/ns/activitystreams#Public" ], "proof": {"...": "..."}}
would be a message (with corresponding Create). http://host.example/actor would acknowledge did:key:z6MkrJVnaZkeFzdQyMZu1cgjg7k1pZZ6pvBQ7XJPt4swbTQ2 by having it in its assertionMethod.
This would lead to portable objects without portable actors. In particular objects that don't need to live on servers.