TrackGuide

Management summary : 
Navigate GPS Tracks using your Apple Watch (or your Phone if you wish).
Details : 
You found a nice track on the internet : a walk through Rome, or an adventurous hike in a national park. You downloaded the track on your phone and started walking but... .
You already carry an icecream and a digital camera in your hands, or Nordic Walking sticks, or you need your hands to climb some rocky paths. No way you can hold that iPhone all the time.
At least, for us, holding our phones while citytripping became a nuisance. And when the Apple watch came out, we wanted to use the watch to guide us on our tracks. So we created TrackGuide.
How does it work?
1 : 
Import GPX or TCX files on your phone to build a library of walks. Or just tap a breadcrumb on your phone to create one.
2
These walks are automatically synchronized with your Apple watch.
3
Select and start a walk on your watch.
4
Whenever you need directions, glance at your watch to see where you are, where you are heading to and where you sould go to.
5 
Some doubts? The iPhone app can always give you more details.

The app is free to use as long as you do not have to send more than 25 trackpoints to your watch.  25 points should be enough to check the watch app out. The iPhone app does not have any such limits, but you need to register if you want to create or modify walks yourself. 
If you like the app, you can buy the unlimited version as in in app purchase. (which is valid for future extensions to the iPhone app as wel).