in theory, the game should be able to be run in steamdeck via steam's proton.
right now, i'm downloading the demo through itch app and will add it as a nonsteam game to steam library and in the preferences select run with compatibility tool "proton Experimental".
i've done this with many other games so far and others have already confirmed that it works for almost all titles on Arch Linux (which the SteamOS is based on).
So maybe all you might need to do is to provide (thoroughly tested) instructions on how to do that.