I believe the GN* sentences are very close or identical to the GP* sentences from what I've seen with GPSTest. I believe many OEMs use "GN" for "GNSS" instead of "GP" for "GPS" to indicate support for multiple GNSS types. You can see that GPSTest treats these as equivalent here - https://github.com/barbeau/gpstest/blob/master/GPSTest/src/main/java/com/android/gpstest/util/NmeaUtils.java#L23.