Seconding all this but especially 4. -- I often buy charity bundles and own over a thousand items. Going through the multi-step process of adding all of these to collections manually and individually is not imaginable.
The filters we do get on the general "Browse" page are great, and even just the ones we get in the app for a given collection -- I have made a collection for stuff I want to check out later, and in there I can for instance filter video games from TTRPGs. I just want to glance through what video games I **already own but don't even know of** because of the sheer size of the amazing bundles that amazing creators offer on itch.io! Or even searching keywords, like when I'm in the mood for something about a specific letter of the LGBTQ acronym within a general queer-themed bundle, or am looking for a specific item I don't remember the exact title of but know is in one of my gigantic collections!
Can we please just get the same filters in our "My purchases/Games you own" page and in bundles?
And/or a setting filter for "Items I own" in the "Browse" page?