sorry for the late post, but thanks for the full run-down! Take your time, since this game is already amazing, and the windows and other builds could also (with the right effort put into them) be great!
I know I am a year late but itch.io has its own app called itch which you can use to download any web games. I agree that learning a build pipeline just for your game to be available offline is a bit much. The only builds I can see making sense are for Android (or iOS too) because itch is a desktop app.