Harris has followed the P-25 Standard on how to package the AVL data in the P-25 Superframe structure from Day-1.
The APCO Project-25 standard has always included where in the Superframe to insert the data, and what format was to be used, which is defined as the standard standardized NMEA format, 'borrowed' from the marine electronics industry. (...Why reinvent the wheel !)
Harris (in Lynchburg) also had the first officially certified APCO P-25 Test Lab under the Project 25 Compliance Assessment Program (CAP) in the USA back in 2009, and was on the DHS's approved list shortly afterward. You only receive accreditation if you follow the standards 100%.
I personally know that Harris' Lat/Lon GPS data displays perfectly on other vendors radios. I have demo'ed it before I retired.
As far as what Moto is doing in their MUPS, I can't answer.
But then, Moto has a history of doing their own thing on occasions.