Itch.io gives us a list of email addresses of people who bought the game
When you implement your store, I'd like to copy this list over (and if possible, have your page ignore all the garbage data that isn't email addresses so we don't have to clean it ourselves) so the people who bought my game on itch will have it on your store so they'd get automatic updates
(I would of course transition from itch.io to your store, I just want the transition for them to be smooth)