I think this is Google's attempt to break into EHR, where Epic Systems is a leader, but has years more experience in maintaining confidential information.
But you're right, Google is a marketing, search, and advertising GIANT. Even if they stay HIPAA compliant, I would want to see more deliberate separation of interest.
E.g. Google provides hardware and software.
Mayo clinic runs the hardware and software, while Google sees none of the data?