No. That's the beauty of federation. Lemmy is not centralized like Reddit. You don't need to be on lemmy.world to see things from it or from other instances like lemm.ee, lemmy.ml, ani.social, etc.
There are exceptions though, for example lemmy.world might be defederated with X instance while some other instance might be federated with that instance X. So you wouldn't be able to see things from that instance X from lemmy.world but from some other instance that is federated with X.
Since Lemmy is not centralized, there's no "official" community (subreddits are called communities here) here. Your instance might have a meta instance community though.
There's nothing like that here, at least not builtin. You can easily code up some bot to implement it though. !asklemmy@lemmy.world had a bot do that once when the fediverse was being spammed by some group.
Note: Do keep in mind that you CANNOT bring your comments and post with you if you want to switch instances. Only subscribed communities and some account settings. There were some discussions about using DIDs and one other tech I forgot to make that possible, but it's not implemented yet.
I spoke with the instance owner of lemmings.world in matrix before and he invited me to try out his webhook system for Lemmy, which is extremely useful. I'll try making something with that. Maybe an automatic system where the bot moderates every community that it gets added as a mod to.
They're better than passwords in that they really are phishing proof and well they are basically RSA key pairs that are generated, so they are naturally brute force resistant. Great for the majority because most people reuse their crappy password over and over again, ignorant of the fact that password managers exist just because they have to spend 10 seconds more to press buttons to generate a password and store them in the db. The tech is great as long as the user knows how to keep them safe.
HOWEVER: Since third party password managers (like Bitwarden, 1Pass, etc.) just recently started to provide support for passkeys, alot of people who wanted to use passkey on first release were locked into big tech bros like Google on Android and Apple on iOS' solutions. And well that's not good at all.
The tech is great though, I'm all for it. You just need to know where to store them. Ideally, I'd store them offline on my device and that exists already but not on Linux (afaik) nor on Android are they a reality yet.
They definitely are not more than secure than my yubikey though.
Note: Do keep in mind that you CANNOT bring your comments and post with you if you want to switch instances. Only subscribed communities and some account settings. There were some discussions about using DIDs and one other tech I forgot to make that possible, but it's not implemented yet.