With the release of Apple Watch Series 2 with integrated GPS many were expecting the GPS data to become available to third party applications like RunGap via "Health".
Unfortunately GPS data is still not available via the HealthKit API and still locked into Apple’s Activity ecosystem and can not be accessed by RunGap.
Luckily several of the third party apps supported by RunGap are being updated to take advantage of the integrated GPS. So, before long you should be able to leave your phone at home while working out and get your data including GPS maps into RunGap.
For details please check out this Review of Apple Watch Series 2 in Runner's World.