This has nothing to do with federation, reddit was a single system and had the exact same issue. It’s simply a result of having communities that overlap in topics, or articles that are relevant for multiple communities.

The key is that each of these posts has a different discussion due to the different community it is in, isn’t that good?

You can’t view subs of a nsfw instance from a non-nsfw instance https://lemmynsfw.com/post/543

You can create a new user on that instance, then you’ll see the sublemmys and posts

If you’re on Android, Jerboa allows you to control font size and feed type (cards, list…) so you can make it pretty condensed. I use List and font 14, and view about a dozen posts/scroll