Im virtually ready to send my Actions on Google App live for Google Home. It uses Account Linking to link a Google Account. I don't handle login as such, I just use the inbuilt routine to detect if the user is logged in and push them over to a Google Auth page which takes care of everything and I get the results back to generate a code.
The notes for submission say that if we're using account linking:
Your agent requires account linking so you must provide a username and password for a test account. Please make sure that any provided accounts are not real user accounts. This information will only be used by the review team, and will not be visible to users.
What is not clear at this step, is what credentials I give to the review team to be able to test. I don't process any logins. Do I need to enable Email/Password authentication in Firebase then or something and on my OAuth page request Username/Password then authenticating with Firebase?