I just found out @Midwest.social exists after finding the Chicago community there. I was trying to list out other communities on that instance and couldn’t quite figure it out. Do I have to visit Midwest.social in order to list them, or is there a way to do it from lemmy.world?
When I first started browsing for new communities that is exactly what I did. I used the browser on my Pc to have one tab with my native instance (midwest.social) and one with the instance I wanted to browse. Once I found something I was interested in I went to my instance, searched with the !community@instance.etc formatting twice (once to discover if need be and the second to actually get to the community). The I could go to the sidebar and subscribe.
It was tedious but helped me get involved more in other instances. browse.feddit.de I believe is a browseable list of communities if you would rather search that way.
Instance A does not know about the existence of instance B until some user on instance A requests a community from instance B; and even then it doesn’t know about all the other communities on instance B.
By analogy with email: You don’t have George Bazooka-Smith in your email contacts, because you’ve never sent or received email with him.
You can use third party sites to find communities, if you’re not seeing them in the search (because they haven’t federated yet) with one of these:
https://lemmyverse.net/ https://browse.feddit.de/
But that’s still going to a third party site so it would nice to have it integrated into the interface.