I don’t get it anyone care to explain

I think most of these things that people (users) want will come from app developers figuring out solutions. A list of each servers fed status and settings to block posts from de federated instances based on your current login, or some kind of multiple account situation where when your current login is de federated on an instance you are viewing it sends the comment on another account that is still federated with the instance you are commenting on.

The app doesn’t necessarily need to use any specific instance at any given time and could very possibly just pull all of Lemmy at once, check what’s ‘hot’ and tell the user if they don’t have any accounts with access to that instances federation when trying to comment.