This looks really neat, but it feels like Apple isn't very keen on biking? I don't think I could replace my Garmin with this until they get better support on that front.
As a cyclist and Apple Watch user, out of curiosity what is your Garmin doing better?
ANT+ support comes to mind
Synchronizing with a bike computer, connecting to sensors (speed, power, cadence, some hrms), triathlon features, battery life (although the ultra here is OK, but nothing like a fenix), strava live segments are a few that come to mind.
ClimbPro, ANT+ for my HRM/power meter/speed sensor, offline navigation, and battery life