[mothered]

So like for example, would an I7 7th gen (roughly £300-400)  require a signature?
I assume phones are fairly pointless to SE, due to blacklists and GPS tracking?

In my experience, a signature was required more so than not.

In terms of the cell phone being tracked, you can disable the sensors responsible for tracking such as the GPS (obviously), magnetometer and barometer sensor. The IMEI will most likely be placed In a pool of blacklisted numbers so upon attempting to activate It with a given carrier, It will fail to do so.