Get the GPS coordinates of a photo in Mac Photos.app
I just tested exporting a file from Photos and it retained GPS information. Are you using Export > Export X Photo(s), or Export > Export Unmodified Originals for X Photo(s)? I used the latter.

To find the actual GPS coordinates there are many, many solutions, but I used the most-excellent command line ExifTool when testing to ensure the GPS information was still present after export.

$ exiftool -gpslatitude -gpslongitude ~/Desktop/IMG_9337.jpg
GPS Latitude                    : 41 deg 2' 14.99" N
GPS Longitude                   : 90 deg 8' 38.55" W


There are many things you can do with this, including scanning an entire directory and outputting their GPS coords to a file, outputting into HTML format, etc. The above command will give you a basic display of it, though.