Okay, got in touch with Drone Deplay and spoke with Ian Smith. They can make the US National Grid display, but NOT on the DJI app. Here is his reply: "
I spoke with my engineers and it seems that it wouldn't be too much of a problem to build that into our service. It would be on our DroneDeploy app though—not DJI Pilot.".
Their app is currently designed for agriculture, construction and mining. Who knows... maybe they can get search and rescue added to their app. After-all, they use mostly a grid system for their aerial mapping and it would work really well for S&R. I will work with him and let you know what I find out.