How does pet GPS tracking work?
A pet GPS tracker estimates its position using satellite signals and then sends that location to an owner’s phone through a network connection. The two steps are different: a device may calculate a position but still need cellular, Wi-Fi or another link to deliver it. Buildings, dense tree cover, terrain, network gaps and battery settings can affect accuracy or how often a point refreshes. For that reason, a tracker is a recovery aid rather than a substitute for an ID tag, microchip, secure fence or attentive supervision. Before buying, check the coverage area, subscription requirements, expected battery life, waterproof rating and whether “live” means seconds or minutes between updates.
Source: GPS.gov guidance on positioning accuracy and signal limitations.