There are old posts about trying to save game progress in html5 games (e.g. https://itch.io/t/186563/html5-game-save-data-locally ) but I haven't seen a real working solution from anybody. 

We can save to localstorage, but that data can be lost - I have players reporting that they're surprised their progress has suddenly gone away!

Is there any updated news about an itch.io storage API?

I'd be happy to use something like PlayFab or Firebase with a custom player ID, but I'd have to get a reliable player ID (e.g. an itch.io account ID name/number) for the signed in player.  I don't think this is currently possible .  Is it?

Thanks.