https://github.com/apple/password-manager-resources
So this is interesting. Apple has a repo containing info on what are the password change URLs, domains that share credentials, and sites that have users append a 2fa code to the end of the password.

GitHub - apple/password-manager-resources: A place for creators and users of password managers to collaborate on resources to make password management better.
A place for creators and users of password managers to collaborate on resources to make password management better. - apple/password-manager-resources