I was just looking over the specs for the GPS engine shown in the Inspire photos based on the assumption of P3's using the same equipment.
It seems that in addition to Glonass it is also capable of receiving the Chinese BieDou sats. and is 'ready' for the EU's Galileo sats.. (Galileo will be the only GPS system not run by military authorities BTW.)
DJI doesn't mention using BieDou but it's interesting that is capable.
The ublox NEO-M8N Coldstart TTFF times are listed below: