From what I remember, the WearOS app will sync the data from the watch with Google Fit, and I don't recall data flowing to Apple Healthkit. I also seem to remember that there is no native Google Fit app for iOS (at least I didn't find it in Canada). Anyone with iOS can confirm?
If you haven't gone through it, here is a support document that shows some differences between Android and iOS:
https://support.google.com/wearos/answer/6056802Click to expand...