One thing is missing and can’t be done with a web app, and that is automatic tracking of activities recorded by smart watches. The work around here seems to be auto-importing them to Strava and connecting Strava to Endurain.
https://developer.garmin.com/gc-developer-program/activity-a...
So what's missing are the integrations from Endurain to the big manufacturers' platforms (if they are missing, haven't checked the code).
Apple Watch -> Health App <- Strava
Strava can directly import workouts from the health app if you don’t like using their app to record your workouts