Unfortunately, it is not really possible to sell web-based games through itch.io (except in a roundabout way that I don't even think would work on iPhones/iPads). If I were to sell through itch.io, it would be the same executable that you'd get through Steam (ie. meant to work on a PC or a Mac).
I might release an Apple Store version later this year, but for the moment, there is no version of the full game that would work on iPhones/iPads :(