There's a powerful search for filtering by country, language or software (#Mastodon, #Flipboard, #Threads, #Ghost, #Bluesky...) & you can easily export the results for batch-following (in Mastodon at least).
I'm always searching for (verified!) accounts, that I missed. If you know some, please send them to @mho@social.heise.de
We (@heiseonline@social.heise.de) have federated accounts on #Flipboard: The problem is, you still can only see the interactions in the app. But there you can't easily switch between two accounts. So I have my private one activated โ and won't see the interactions.
And you're right: For accounts from organizations, that are in the #Fediverse a federated account on Flipboard is not of much use. But there are some, that aren't otherwise reachable from the Fediverse. (RSS is another story, that's true)