I’d love to get it on my Samsung watch too. But…
Unlike Phone OS, there are many different Wearable OS - there are atleast 10 different OS right now. I don’t have the actual percentage of distribution, but looking at smartwatch sales, Tizen should have the biggest percentage. for smartphones Android and iOS run on 99.5% of smart phones. But for watches, OS other than Apple’s WatchOS and Tizen on Samsung watches, others also have a big percentage (fitbit, garmin, pebble etc…). Therefore, to cover many people, there should be 10 versions of the same app. This doesn’t make a good case for making a Watch app.
All said and done, Why not? 