Drop the "c" and you've got it about right. Professional grade receivers such as Trimble's Nomad series can do 2-5m accuracy before post-processing, and 1-3m afterward, which requires downloading the points to a PC and correcting them based on satellite information received at nearby base stations, and that's with good satellite lock (perhaps 6 or more) and staying away from large vertical obstructions like trees and utility poles that deflect or block signals. Licensed surveyors can get accuracy at the centimeter level only by using very expensive antennae (USD$10k range) and occupying the same point for hours, taking an average of thousands of readings. And then as some posters here have said, vertical accuracy is still only about a third as good as horizontal. I think 10m with a phone is not impossible given that it is probably indoors or in a car, or while moving, and considering satellite lock comes and goes. The chip's primary duty is to supplement or correct info given to E911 dispatchers, and so it probably doesn't get much better than differentiating one single family home from another.
