I wouldn't trust a closed-source solution to be the privacy-focused identity provider. And with "Apple Search Ads", Apple could also be considered as an advertising company.
I have actually started out to create a privacy-focused SSO solution named "Sign In with SimpleLogin" [1] before "Sign in with Apple" was announced. The solution is from the beginning meant to be open source and even self-hostable. It's superior than "Sign in with Apple" in several ways:
- The dev experiences is far better
- The random email part is customized
- Name, avatar could also be customized
If you visit the home page, you would notice that it's talking mainly about the email alias part as the SimpleLogin button is not implemented on popular websites yet, which hopefully will come soon.