how to give FREE access to your app to Apple Review Team?

so in google play store, i simply generated a PROMO Code which usually suffices and google review team using their own google account for sign up so no need of credentials as well.

my app only has social logins (apple and google), and i figured that sandbox tester username password isn't used by apple reviewers, so i'm wondering if anyone has been through this

ideally i don't want to change the code of my app to give secret access, is there a way to give apple reviewers full access and a way to get them a social login for testing purposes?