I think it is legal indeed to filter candidates by these metrics prior to the interview. As a hiring manager at a previous company, I was explicitly told by HR

I think it is legal indeed to filter candidates by these metrics prior to the interview. As a hiring manager at a previous company, I was explicitly told by HR to automatically move all female candidates to the phone screen step, regardless of their resume, to improve our chances to get a "diversity hire". I assume HR knew what they were doing from the point of view of the law. That being said, this is just one anecdote. I have not seen it at another employer. I don't know how common it is.