@masterspace @mango_master @Kichae
…
If that’s given, every entity (@‘person, @‘community, …) on each instance is unique.
Therefore, there can never be a duplicate identity = <entity>@<instance.domain>
Which allows the general assumption (all implementations adhere to the standard) each instance (homing instance, where the user is based) can verify the every identity within it’s domain.
…

@masterspace @mango_master @Kichae

The matter of fact is , just in simple terms for SSO to work, every fediverse implementation has to agree on a standard for federated authentication.
Maybe, I’m just not seeing the issues or don’t really grasp fediverse and it’s implementations yet.

My idea, every fediverse instance is unique (no matter the implementation, i.e. mastodon, lemmy, pixelfed,…).