Yes. You will not see content from an instance that has defederated your home instance or that your home instance has taken action and defederated from.

The search in Jerboa is…limited. It searches on community name(not display name) and it will only show about a dozen of the largest communities as results and nothing more. You essentially need to already know what you’re looking for to find a great deal of value from it.

You really have to search for communities externally if you’re looking for something that isn’t a niche interest. There’s a small handful of directory sites that help with this, but I can’t for the life of me remember them at the moment if someone can help me out 😅

Edit: Mentaledge beat me too it. Lemmyverse.net is the largest of them.