This study evaluates the positioning performance of non‑survey‑grade GNSS devices (smartphones, sport watches, and IoT trackers) across open terrain, urban canyons, and forest environments. A spatio‑temporal synchronization framework with decomposition into along‑track and cross‑track error components is applied using a post‑processed geodetic reference. The results reveal pronounced generational differences among tracking devices, strong environment‑dependent performance degradation, and fundamental physical limits of low‑cost GNSS relevant to tactical and autonomous applications.