I read a few of the things you said here and I have a few points to say :
1. Steam and FOSS don't seem to be so incompatible. A few FOSS games already are on Steam, like Battle for Wesnoth, Teeworlds or Warfork. These are not just "free" games, these are free and open-source games, and have always been. There's even the most popular teeworlds's client as another Steam game, which is also FOSS.
The only thing that matters and that might cause problems with licensing are if you want to use the Steam API to port achievements, steam id stuff and such into the game, which won't be an issue I guess for the game.
2. Steam is evil, I get it. But I don't get why Microsoft Store and Epic games wouldn't be as evil, if not worse. But I get it if you're against using Steam for political reasons. Although, I wish you do not mix your political views with some elitism about knowing a cool secret game nobody knows.
3. I know I can add custom exec files to my steam library, I already do. I didn't mean to go on Steam for my own practical use. Steam has a promotional effect and makes it easier to get people involved in playing your game, when it's a "one click" action in a client rather than going on a shady website (people are scared of anything on the net nowadays).
4. There's no question of quality over quantity. The game is the game, the community is the community. What I want for this game is for it to be played. I get it that some of you probably want to stay in their closed community they've known for years, but I think the purpose of a game is to be played, and I wish you would promote it on the places where you get the most exposure. Most people use Steam because it's the simplest platform and that with the most available games. People looking for new games to play use Steam more than any other platform. EGS is mostly used for the free games and microsoft store doesn't exist.
Steam also has an advantage of having a pretty simple procedure to add your game on it, although it costs some money (which I'm ready to participate in paying if you guys are up for it).
5. Steam doesn't mean exclusivity, and you already have a launcher doing the work pretty well.
I answered in a kind of messy way to a lot of things I saw in the conversation, so sorry if some of you feel target for no reason, I was just answering to a patchwork of your replies (and I didn't read all of them :x)