itch.io

I play with it added as a non-steam game and it just kinda works.

This is likely due to Linux being a second class citizen in most large developers eyes. They want to make one to sell to Linux users, but aren't will or able to put in the man hours to do it to a high enough standard, or maintain it. There are a few good examples of Linux ports running better or the same as their Windows counterparts, games like; Counter-Strike 2, Stardew Valley, Divinity Original Sin, Hollow Knight, Crusader Kings 3, Valheim. Not to mention some fan made community ports such as OpenMW (The Elder Scrolls III: Morrowind port), Arx Libertatis (Arx Fatalis port) and DevilutionX (Diablo port).

EDIT: Add Baldur's Gate 3 to the list of good native ports as of recently.

While a native Linux build would be great and I'd fully support it, At least with Nose being the main programmer (unsure if he might even be the only one) I doubt its viable with Linux specific bug fixes being needed (not to mention we are in an odd transitionary period between X11 and Wayland, which would also need to be addressed by Nose). For the time being the WINE and Proton compatibility layers work fine, with little to no performance degradation or visual bugs (which I've seen at least, playing the game as a full time Linux user). Maybe it will be considered once the game reaches beta, but I wouldn't hold your breath. At least the launcher/updater Yeetpatcher has a native Linux tool.

Unfortunately from my comparison with the Internet Archive, they just changed the link text for the website and the version archive from my comparison. Still, stuff is happening

I had pretty good success adding it as a non-steam game and using proton, runs flawlessly for me at least on Arch with Nvidia. Personally I use the latest Proton-GE for best results.