This application has been mainly made because of the flawed implementation of HealthKit in Zwift (at least it still is flawed in the Companion version 3.0). This reads Garmin Fit files and exports the data correctly to Health Kit.
The app has to potential to be used in other scenarios as well. Feel free to do your changes and adaptations.
I would love to make this application available in the App Store but I'm not sure what the licensing requirements are for using Garmin Fit files.
This project heavily relies on FitDataProtocol made by Kevin A. Hoogheem.