I would bet that doing so would be a pretty quick way to have your app pulled.

They already require that you use Sign in with Apple, I would think that it working fully is also a requirement?

You can use Hide My Email on any website though, whereas Sign In with Apple is limited to just those websites and apps that support it. Sign In with Apple isn't nearly as popular on the web, so it's a lot easier to just ban "@private.icloud.com" from your web service there.

> They already require that you use Sign in with Apple, I would think that it working fully is also a requirement?

They require apps offer a service which meets their privacy requirements if they use any 3rd party or social login service.[1] And apps could block private.icloud.com for email and not Sign in with Apple.

[1] https://9to5mac.com/2024/01/27/sign-in-with-apple-rules-app-...

Hide My Email isn’t particularly related to apps. You can use it on any web form that asks for your email address, or as the sender of any email message you send using Apple Mail.