The "other platforms" documentation is "make this request, store some data, follow redirects". No code, no helpful links on how you might accomplish these things, nothing. You get the bare minimum.
I'm not saying its impossible, and neither is the article. I'm saying that Apple clearly doesn't care about supporting a platform as huge as Android, and that clearly signals to multi-platform developers that they are on their own.
[1] https://developer.apple.com/documentation/authenticationserv...
[2] https://developer.apple.com/documentation/sign_in_with_apple...