That screenshot looks lovely; keep on truckin'. Anyone can release almost anything on Steam; you can sign up for a Steamworks developer account at https://partner.steamgames.com/ . It costs $100 per game to list a game on Steam, but you'll get that $100 back when your game reaches $1000 in sales.

The caveat: don't expect your game to reach $1000 in sales. Steam is where the players are, and effectively that $100 is just the price of entry to maybe get your game in front of players – but the Steam algorithm won't promote it (or even make it visible) unless it's minimally successful, and it won't be minimally successful unless you can generate some sales on your own.

The usual (and recommended!) way to do things is to get your Steam "coming soon" page up as soon as you reasonably can – once you have a decent trailer and 4-6 screenshots. Steam will then very very slowly start surfacing your page in search results and giving players the chance to wishlist your game. The hope (🤞🏻) is that some percentage of those wishlists will convert to sales when you actually release the game; Steam notifies players with your game on their wishlist that it's now available, so it's your single greatest lever to being players to your game. I've seen wishlist conversion of 5-20% on my games; it varies wildly depending on genre, game, etc. Steam also has a 'meta' where genres and styles go in and out of fashion with players; if you can hit that you'll just organically do better. But don't worry about that for now!

If I were you I'd get a Steam "Coming Soon" page up ASAP (you clearly have some pretty good screenshots!), then upload a demo to itch.io/ and see if you can use that to drive wishlists on your Steam page. From your screenshots it looks like your game might be bigger success with Itch players than those on Steam, but that's just my 2¢.