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
There is no code so big, twisted, or complex that maintenance can't make it worse. (Gerald M. Weinberg)