The Itch.io version includes a steam key, so it doesn't really matter where you buy it (although I get to keep a larger cut if you buy it on itch.io). And for your earlier question, if you buy the early access version, you'll get the full game when it releases (free updates), but if you wait until the full version releases, we will be increasing the price of the game at full launch (so you have to wait for updates if you buy now, but you get a discount for supporting us early).