This repo contains a library for the FIT protocol. FIT is used by many sports devices, like the GNSS-enabled watches made by Garmin, to transmit physical activity and health monitoring data. There are also some utilities for common tasks like translating to GPX.
Important
This is an unofficial and unsupported library. It is currently suitable for basic tasks like parsing simple GNSS recordings, but I haven't tested it with anything else. If you need something more stable, you will be better served by one of Garmin's official SDKs.