Sure, nobody is stopping you to have local users (e.g. admin) and oauth users at the same time. But then I don’t understand why you are trying oauth immediately ( oauth_auto_login = true) -> users are not able to get access to local user login form.
Users don’t have Grafana accounts, they have access to Grafana if they have to our app (where Grafana is embedded), the auto_login behavior is very important to us. But we still want to be able to login to the admin using the login form.