A community to find other communities in any of the Lemmy instances.
Probably something from feddit.it ?
I'm not sure that searching for a community by its home instance works.
You can browse for their communities here:
https://feddit.it/communities
But then you're on there and not where your account is.
You could take that community's URL and search for that on your home instance search, then subscribe, etc.
Nevermind, piefed actually works correctly in this regard and you can just search like this:
https://piefed.blahaj.zone/communities?topic_id=0&feed_id=0&language_id=0&search=feddit.it&sort_by=title+desc
Then again, that only works for communities your home instance knows about.
If there's a community you find on a remote instance, that your home instance doesn't know about (nobody subscribed yet), then grab the remote community URL and search for that on your home instance, you should then be able to subscribe and others won't have to jump through these hoops.