ohhh personally I just look through the twine tags but here is a collection I found of Interactive Fictions here in itch
To get you started, the (what I'd consider) holy trinity of IFs in itch are: Scout, Wayfarer, and A Tale of Crowns (I'd also add Misplaced here but it's less known afaik). Unfortunately, they're all still ongoing.
It's really hard to find complete IFs here but the ones I've found so far that I also enjoyed are:
Plunder that Booty (free)