In fact a lot of the satellite tracking status does not seem to be available in the documented part of the Garmin protocol, but is readily available in their NMEA output. The Garmin protocol is mostly useful to download waypoints and tracks off of the GPS receiver, but gpsapp doesn't use any of that.

The garmin and taip protocol decoders are going to disappear, they just aren't providing anything useful and any receiver that speaks either of these also has at least NMEA.