I’m sorry, I wasn’t sure you were talking about your own game(s?). For that answer you’d probably have to ask an admin.
While I’m sure they would accept… voluntary transactions(?) from you and just trust your math, I’m kind of doubtful they would have some sort of universal plug-in that fits all game engines and keeps track of earnings.
All that being said, personally I view in-game purchases as morally questionable if we are talking about paid games here. If you are so eager to share with itch, why not make the currently purchasable content earnable through gameplay and add other things to your presence on itch.io for players to buy if they want to support you further? Like art books, outtakes, scans of development notes (if you still have them), making of videos, and the likes. I’ve even seen paper cut dolls with a game once. The sky is the limit. :)