Google allows you to facilitate a specific service agreement addendum to ensure that your Workspace services are HIPAA compliant. This would only cover how Google manages any data housed in that Workspace. Your org would still be responsible for configuring the Workspace in such a way to prevent any accidental access to data between projects, but this is a relatively simple process to do with OUs and Security Groups.
https://admin.google.com/terms/cloud_identity/3/9/en/hipaa_baa.html