I think we have enough to propose an update to RFC 8141 URNs
Anything to the left of the '@' refers to a device/bot/agent operating on behalf of a real entity specified on the right side of the '@'
e.g.
myphone@trbouma.bsky.social
If operating in a strictly local context, it would be @myphone
Also the entity could be referred to as @trbouma.bsky.social
Note: my use of Bluesky examples should not be viewed as an endorsement.