Android Team Awareness Kit (ATAK)

The Android Team Awareness Kit (ATAK), for civilian use (https://www.civtak.org/), or Android Tactical Assault Kit (also ATAK) for military use - is a suite of software that provides geospatial information and allows user collaboration over geography.

ATAK is a smartphone geospatial infrastructure and situational awareness application designed for military and civilian use. It provides geospatial information and allows for user collaboration over geography, enabling safe communication and coordination over maps and geographic features. ATAK was developed by the Air Force Research Laboratory (AFRL) and is now maintained by the TAK Product Center (TPC). It integrates various types of geospatial intelligence products such as maps and elevation data to enhance situational awareness and mission planning capabilities.

This video (https://www.youtube.com/watch?v=WXuQERL_e8M) - Move, Shoot, and Communicate with ATAK (and alternatives) - by TREX explains ATAK in more detail, and provides some useful alternative options to using ATAK. I note that the TREX video is four years old, and that there has been improvements and additions to off-grid mapping and communications strategies during that time.