Can't happen. At least two reasons, probably three:
1) characters are made with a version of Honey Select, and images made with it cannot be used in any game sold commercially (it is a game itself, not a dev tool) only by subscription/donation methods as here.
2) Given that restriction, I would imagine that some other images, especially easter eggs, are similarly limited.
3) Even both of those things were untrue, If you put up a game on Steam, you can't have it available anywhere else for less money, so it would no longer be free on itch, either.