But they are very restrictive with API access. You have to apply for a developer access, and they won't give you any if you aren't a developer.
All the "modern" companies will give you an API access, a token and even API wrapper code in many languages in an instant. Garmin is very old-school here.
Very old school indeed. In my job we tried to approach them. They have a very interesting library that allows your app to connect to their devices and skip their app. It's for research only. They kindly offered us to use it but when we mentioned that our app was open source they pulled the offer. We tried to explain that we could bundle their library in a proprietary module but they didn't want to listen.
All the "modern" companies will give you an API access, a token and even API wrapper code in many languages in an instant. Garmin is very old-school here.