This sketch for the Arduino Mega 2560 reads: 1) raw Nexus sensor data, 2) Nexus server NMEA data, and 3) Garmin GPS NMEA data. The data from the three sources are output on the Arduino's Serial port in NMEA-style sentences.
MIT App Inventor 2 app that receives NMEA sentence-formatted BLE data from an HM10, strips out the BLE delimiters from the data, and writes complete NMEA sentences to the Android device's SD card.
Paul Mathews