[kettro]

Ex Garmin employee: The amount of 1st party software in those watches is astounding. And it almost all gets processed on-watch.

The 3rd party app support is laughably poor, but the APIs are there. ConnectIQ apps are written in their own language (MonkeyC, which is kinda hard to use), which hinders adoption, and are generally slow and feature-poor.

But the good thing for Garmin is that the 1st party software more than makes up for the lack of 3rd party support. The music-enabled watches (eg FR645) have Spotify support, GPS, and Bluetooth music, last for an eon, and are hardy as all hell.