you can export your own apple XML data for usage and processing, but if you want to create an application and request apple XML data from users, that likely crosses into clinical research territory with data security policy requirements and de-identification needs.
- aidlab.com/datasets
- physionet.org
I don't even trust Apple themselves, which will sell your health data any insurance company any minute now.
The reality is that no matter how ethical the company you trust with that data is, you're still one hack or pissed off employee away from having that data leaked, and all of that data is freely up for grabs to the state (whose 3 letter agencies are likely collecting it wholesale) and open to subpoena in a lawsuit.