We are currently using "Sign in with Apple for the web": https://developer.apple.com/help/account/configure-app-capabilities/configure-sign-in-with-apple-for-the-web/ but we do not publish apps on the App Store.
Because of corporate re-structuring, we need to migrate to a new Apple Developer / App Store Connect account. So we are looking to migrate "Sign in with Apple" users to the new account.
Apple does provide guides on how to do it: https://developer.apple.com/documentation/technotes/tn3159-migrating-sign-in-with-apple-users-for-an-app-transfer but unfortunately, it only works if "Sign in with Apple" is used with an app published on the App Store (it requires app transfer).
Who should we handle this case? Please help.