They only use the internet to show the location on a google map. If you don't need the dot on a topo map, you don't need the internet at all. You still get all the data in numbers. Distance, direction, altitude, lat lon, etc. I used mine without internet on a tablet with no internet for a long time and still do. I don't use DJI software because I don't want it requiring any updates before I can use it. I use Litchi software and anyone who owns a DJI drone should buy it. It is about $25, but well worth it. You get better software and it allows you to make your own routes with waypoints using their web site. You can post your flight route online for others to use , or you can download flights others have taken. An example would be a perfect flight someone else took, but the day was a bit cloudy, you save their route, hit the auto pilot and it flys the exact route automatically. If they have uploaded a youtube video of the flight you can click on the link and see how it looks. I made multi path grid searches of my personal area for finding planes or just scanning my area for things. It flys a exact altitude, speed, camera angle, and pattern so I don't miss anything. If you get fancy you can do a few of the same grid, while changing the automatic camera angle to account for the sun messing with your video. You can look up numerous other flights others have taken on Litchi and watch it here on the net. I can make a flight while at home on my big screen monitor, then employ it in the field.
The mavic pro is a proven platform. The flight time is about 27 minutes, and the remote and video has a range of about 5 miles, much better than the smaller ones with a mile.