Google just release Privilged Access Manager which might be a better fit: https://cloud.google.com/iam/docs/pam-overview

It's available: https://cloud.google.com/iam/docs/pam-overview

A very late response for people finding this through a search engine. There is new documentation in the GCP Architecture Center describing a solution for just-in-time privileged access to projects which might be helpful: https://cloud.google.com/arch...