[vezuchyy]

I don't have Apple Watch, but have Garmin. I used the store once during the initial setup and I don't see why it should be different for AW users.

[Jtsummers]

A lot of Watch apps also get installed through the attached iPhone when you install the associated iPhone app. I think it was the default, I turned it off, to have "Automatic Downloads" on for apps. So if that's still the default (or the present setting for the watch) then if you download Strava for iPhone you'll get Strava on your Apple Watch without ever touching the Watch App Store.

[izacus]

But it's still Watch App Store which installed and delivered the app right? And the developers must use it to give you the application?

Just because you didn't open the UI it doesn't mean the developers weren't forced to go through that app store to reach you.