GPS Connector

On my Samsung galaxy S25u I see a sentence in the app's NMEA terminal output like:
I can't find a definition in any NMEA docs, is this an android API specific thing or something generated by the GPS connector app? I'm intrigued by the "bluesky" part - the only bluesky I know is the GNSS firewall manufactured by Microchip

Looks like an NMEA-pseudo message from your Samsung phone.
All proprietary NMEA message start with prefix "$P" followed by three-letter manufacturer code.
So "SMS" - i guess - stands for Samsung. The "G" maybe for Gyro? I don't know.
You have to ask Samsung to get more information about that message.

Regards,
Markus