Does the GPS Module return Altitude as looking at some sample code I see it might not, and coding for the device I don’t see altitude in its returned values. Two more days till its in stock and I’m planning on ordering one as the current project needs it, and while missing Altitude isn’t a killer, it does hurt and the FAA isn’t going to be happy.
In general, if a GPS has a 3D fix, it can output altitude. You’ll find it in the $GPGGA sentence, see GPS - NMEA sentence information for details. Whether or not this data is parsed and exposed in the Seeed driver is another matter (which I have not looked into).