The Lynq product is simply a 900mhz transceiver, a GPS receiver, an accelerometer, and a magnometer. They are definitely not using device to device relative positioning. A smartphone and a GoTenna have all of the same functionality.
The NS Dashboard App in combination with a GoTenna actually does all of the things the Lynq product does. You can even configure the map to be oriented to your heading, which will then make the location of other people be relative to where you are standing and what direction you are facing. The NS Dashboard App has the added benefit of showing an actual map too.
The NS Dashboard App’s main purpose is to serve as a dashboard for a snowmobile or ATV, but you don’t need the NS1 Gauge System hardware to use the app. In addition, you can easily change the screen to simply show the map with no gauges.
You can find details on how to use the Location Sharing feature of the NS Dashboard app starting on page 38 of the NS1 Gauge System User Manual.
One thing to note is that there is an update for the NS Dashboard App that will be released in the next two weeks that will drastically improve the ability for the app to know what direction you are heading. At the moment it only uses GPS based heading information, so you have to move in a direction for a distance before the heading will update. After the update the accelerometer and magnometer, if present, will allow the heading to be updated every second or two.
Here’s a screenshot of the NS Dashboard App’s Location Sharing Feature in action (note that in this screenshot the gauges are present, but they can be removed):