What GPS do you have?
I was always under the assumption that all these virtual o apps were used on phone and that wasn't really appealing. Assuming the coordinates could be calibrated accurately, having this on the watch actually has potential.
Garmin 735XT
Hard to be 100% accurate for a few reasons but you can have the watch 'punch' at between 5 and 20m.
It's just an app for punching when orienteering so could make a training course without controls that bit better with the confirmation that you are in the right place.
Not checked but i'm going on the assumption that the co-ordinates need to be LAT/LONG because that's what GPS use, so that may have a bearing on your map.
Handy, I've the same watch. I think the punching could be useful even with 20m for training.