[bgentry]

Quoting from the page linked above:

Sign in with Apple works natively on iOS, macOS, tvOS, and watchOS. And it works in any browser, which means you can deploy it on your website and in versions of your apps running on other platforms.

So it at least sounds like it can be used anywhere with a web login flow. Although the docs say this must be accomplished using their JS library, as opposed to a standard OAuth2 flow of some kind: https://developer.apple.com/documentation/sign_in_with_apple

[apenwarr]

Cool! Maybe it's more doable than we thought.