When I see a game under development that is interesting, I add it to a private collection like "Interesting games". Over the years my collections have gotten 100s of entries.
1. Now what I would like to do, is to search my own collection. Like, perhaps "Status" changed from In development to "Released"? If so, I might now want to make a decision if I want to buy the game.. but I cannot search my collections? Opening up many 100s of games just to recheck their status is mind-boggling tedious. So I often miss when they are completed and I guess I just buy a lot fewer games.
2. Also after I do buy a game, I likely want to remove it from that collection. Why can I (from the game's page) only add it to a collection, but not remove it? This is also true if I want to move it to another collection. Like perhaps the game is released, but I find it a bit too expensive, so I want to move it to a "Wait for sale" collection. Again, I can add it to a "Wait for sale" collection, but it would be good if I at the same time could remove it from my "Interesting games" collection. It should be a simple fix, there are even 3rd party scripts to do this (https://greasyfork.org/en/scripts/433692-itch-io-simple-remove-from-collection), but we should not have to rely on 3rd party scripts for such simple things.
3. If/when search is implemented. It would be good if I could search for things like: Has an ongoing sale? Are currently buyable in a bundle? Have more than 1000 downloads? Have a score over 3 and at least 100 voters. Last activity, was it was more than 2 year ago, or less than 3 months ago? Things like that. It will increase your sales!
4. It would of course also be good if I could also search "Things you own" (my bought games), and not just my collections. Because sometimes I do buy things in development and want to wait with them while playing finished products, or I might want to play the most popular games first or so. But worst case I guess I could just spend some time to add them to collections too.