Hi @real_kiwi -
This rather long thread ended up with a resolution to a bug in the Tritech software!
While that thread was dealt with in the old days of Companion OS, parsing an NMEA stream to show vehicle position on the map should be possible with BlueOS. There are two approaches, using the NMEA injector or parsing the messages directly with ArduPilot.
To better advise, can you share your goals for the BlueROV2 equipped with this payload?
A quick search also yielded this thread