@afewbugs @aku @leadegroot @Gargron I came with exactly the same question. About 80% of the things in my feed are cats and dogs, and sometimes I want to just see the cute animals, other times I want to just see the things in between them.
The other thing I'd really like for decluttering my feed is to not see replies to a post if that post is in my feed. I unfollowed someone today because a huge amount of my feed was filling up with their followers replying to their posts, which they then boost. And, because the feed is in reverse-chronological order, I see the replies first, so if I do click on them I then see the entire thread.
But my number one feature request to Mastodon would be stop doing whatever you do that breaks open in new tab. Given that both the back button and opening in new tab are broken, navigating in the web app is far harder than it should be. If I click on a post and come back, I lose my place because the feed is refreshed in the middle and I end up somewhere random. If I try to open in new tab so I don't lose my place, it doesn't work (the least discoverable bit of UI: The date in the corner actually does let me open in new tab if I click on it, but it does so on the original instance that made the post, not mine).