Saving Authenticator Code For Account Using Sign in with Apple

I have an account which uses "Sign in with Apple", and the website recommends I setup a two-factor-authentication using an authenticator code. I would love to use the new Apple Passwords app to save that code, but if I scan the QR code to setup a new code, the app tells me I am not allowed to save an authenticator code for an account using Sign in with Apple. And it won't let me save the code unless I fill in a website, username and password to go with it.

Do I just have to make up a bogus account and then deal with it trying to auto-fill bogus info when I log in, or is there a way I can save the code and link it correctly? Seems silly that I have to accept reduced account security if I use Sign in with Apple.