It's not the same but I have this, a completely separate signup page https://github.com/flamarkt/signup-page . It is tested to work with social login for new or returning users.
It wouldn't require many change to be a login page instead. I'm not sure if I want to add a toggle for login in the same extension or create a second extension though. I was considering placing login and registration on a single page, which is common for e-commerce.