If you have any elevation changes between the points, the typical gps map functions will give you the ground distance. This will not be an accurate distance for shooting. You would need to know the angle of the slopes and height plus using cosine to get the exact distance.
For example...
I was thinking of purchasing a McGowen 26” barrel 1:8 twist for my M70 push feed .270cal. I don’t reload, so I wanted to use the Hornady Precision Hunter cartridge. My goal was to have a rifle capable of 900yds with 1000fpe. Any thoughts?