Google's Health Connect system doesn't share this data either (without a consent prompt for third party apps, off course). This is to the point where I wish it would just support some kind of sync, because two devices hooked up to the same accounts need a third party app to transfer the health info.

Apple is subject to the same laws Oura is. The competition is too.

I believe the Apple one is E2E encrypted so they physically can't give useful data. Thats the core issue with Oura here.