I got pygbag to work, but I don't know how to put it into itch. Itch said I needed index.html, but pygbag didn't output that.
what i used: py -m pygbag --app_name Runner! --title Runner! --package runner "C:\******\main.py"
So, what did pygbag export?
A folder called build. It didn't export it. It just left build so I assumed it's the output.
So, look inside it. See which file you're supposed to open in the browser. That one should be named index.html, and if not, you can fix that.