Currently the most common and advanced practice I've seen is the FHIR format (https://www.hl7.org/). This is not your usual step-tracking app, it's a data exchange format for hospitals and clinics. I think that's what this release is about because I know that Google has been interested in the FHIR protocol specifically. Microsoft and other large corporations are also exploring FHIR and similar systems, it's not as dreadful as you might think.

It looks like the idea is to bring the real data sharing protocols to the patient level, which is going to be an interesting challenge for them.

The comments regarding traction etc. are all valid, there are many angles in the healthcare technology business. Google might be one of the few companies which can get the money and momentum in it. Whether that's desirable or not is for you to ponder.