Thank you so much, we're really glad to hear you enjoyed the game!
Please don't feel pressured to pay any extra for getting the game from the bundle, we're really glad so many people donated to charity and also got to enjoy our game!
If you still want to do it though, buying it from itch would be the better option, and you'll get a Steam Key (the Steam version has trading cards, emotes, backgrounds and, eventually, achievements, and it also updates automatically).