Which GPS should I buy ?

Nick-H

A GPS device, unless it is a tracking device, which reports its location to a base station, as in fleet tracking, emergency beacons, and so on, does not give out or transmit your position anyway. It works it out from signals received and tells you.

Of course, unless you are unconscious, you could pass that on --- assuming that you are in range of a cell, and have a signal.

A GPS device does not turn a phone into something that tells people any more about where you are than any other phone.