Apple Watch is probably < 1% of a market dominated by Garmin, Polar, and Suunto, so it doesn't make much financial sense to integrate with GymKit.
Apple falls to Garmin in two areas: battery life and software. Sleep affects recovery, so planting a watch on a charger every night is a non-starter. Garmin's performance analysis software is also years ahead of Apple's. Apple could fix both of those things but that would require investment which I'm not sure they are willing to make.
Apple falls to Garmin in two areas: battery life and software. Sleep affects recovery, so planting a watch on a charger every night is a non-starter. Garmin's performance analysis software is also years ahead of Apple's. Apple could fix both of those things but that would require investment which I'm not sure they are willing to make.