Hi zingrook!
Sorry for the slow response and for not clearly communicating about the Steam keys. Steam and itch.io may be different platforms and thus different services and businesses too, but I would really dislike to sell the same product multiple times so that my customers can have it and play it on multiple front-ends/machines etc...
So I added Steam keys to the itch.io system. Now you can request your Steam key on the store page if you bought the game, it is included.
Thanks for buying the game and thanks for the kind words. I'm happy, that you are enjoying it :) !