I found out yesterday that if you download the itch.io launcher it actually does have the filtering capabilities I was after, which makes it all the more strange it's not available on the website
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Yeah, I agree itch.io site could do a lot better. You can use third party solutions such as Random Game Bundle at https://randombundlegame.com/?bundles=ukraine or my spreadsheet but as search is broken its still sometimes rather difficult to find games you want to download on the download page.