"without turning over any of their personal data to a third-party company" Uhm.. If a user sign up on my site with apple sign in then they definetly will share

"without turning over any of their personal data to a third-party company" Uhm.. If a user sign up on my site with apple sign in then they definetly will share personal data with a third-party: Apple. If user A wants to use product B and signs in using solution from C then C is the third-party.