thefatwookie

those apps that use Sign in with Facebook/Google WANT that user data so most will most likely NOT offer the sign in with Apple on their apps, sadly

You've got it backwards. The service gets to see what sites you log into - that's how they track you. The upside to using them, is that your site can possibly be plastered all over those services via that users account. The incentive to using something like Apple badge is that you may attract more security/privacy conscious users to your site.

I, myself, do not have an account for either Google or Facebook. So the apple badge will be a welcomed addition.