I really wish Garmin had an official API that can be used by their users instead of the reverse-engineered solutions (although they're very good), but they're at the mercy of Garmin.
Thanks for the tip! I run these things mostly for fun - the Spotify stats thing isn't super useful, but it is fun to look at how my listening habits have changed over the years.
It slightly more than just an API though: one can't aggregate directly from the Spotify API.