That’s something I think is possible on itch - have a “this will be played in the browser” upload demo or teaser, and then also the paid download. I think you can do both on the same page?
[returns breathlessly]
Yeah, itch can play an HTML file in the browser directly, you could just toggle it “this file will be played in the browser” so it doesn’t even require a download for the demo - sometimes it’s an easier demo if you don’t have extra download clutter…