What's the intended purpose here? To update online statuses or something else?

Updating APIAcccess.Friends list to match current state, mainly for the dashboard friends display to stay updated.

As in if a user adds a friend from the website or something like that? We probably want to wait for a push based event flow to come online before considering this. I don't think it's important enough to be polling, let alone every 5 seconds. Maybe once every hour, or if decided better, when the overlay is opened.

As the original issue was opened by me, I would guess the intention here is to update the Online status of the friends list, as they don't update at the moment.

This needs super high priority. It's a core foundation of osu! that you know when your friends are online.