I use the gpsd tool set since a while. In Debian it is available as package or you can find it here: gpsd
Several programs from the gpsd tool set worked as expected when I use it with a ZED-F9P. Not so with the newer ZED-X20P. The reason is simple. When starting the gpsd process it initialize the F9P and others u-blox devices with several messages, but not so with the X20P. The X20P stays in the factory default setup.
So I saw that gpscsv -n 1 -c SAT didn’t work. With help of several resources I could initialize the X20P in way so that gpscsv is working. These are the parameters

  ubxtool -z CFG-MSGOUT-UBX_NAV_PVT_UART1,1 
  ubxtool -z CFG-MSGOUT-UBX_NAV_SAT_UART1,1 
  ubxtool -z CFG-MSGOUT-UBX_NAV_SIG_UART1,1 
  ubxtool -z CFG-UART1OUTPROT-NMEA,0 
  ubxtool -z CFG-UART1OUTPROT-UBX,1 
  ubxtool -z CFG-MSGOUT-UBX_NAV_TIMEGPS_UART1,1

Of course I cannot say if these are all parameters which are set for F9P and others but at least for my gpscsv issue with ZED-X20P is it working. Currently I am using gpsd version 3.27.6. Maybe in later releases it will work.

See also: ZED-X20P