The only thing I love about Bluesky / AT Protocol is the use of subdomains for user names.
The double-@ is confusing as heck to people, but a link that also works as a mention name is obvious / intuitable (eg "Find me at jeremiahlee.bsky.social which makes me mentionable @jeremiahlee.bsky.social").
It's probably too late to fix this in the #fediverse, but I wish we might try. #Bluesky #ATProtocol
From what I remember, that sort of thing was one of the goals when #BlueSky was being designed as user-focused instead of instance-focused like #ActivityPub.
Maybe not that *specific* thing, but the general ability for users to manage their identities more on their own. Which includes users finding such unanticipated use cases :)
It's part of the general account portability that platform offers.