Both of my dogs have the Whistle GPS. Whistle was originally only a fitness tracker. Last year they acquired the company Tagg which was exclusively GPS for dogs

Both of my dogs have the Whistle GPS. Whistle was originally only a fitness tracker. Last year they acquired the company Tagg which was exclusively GPS for dogs. After the acquisition, Whistle redeveloped the app and the underlying tracking service. Many Tagg users (myself included) felt like Whistle made the GPS capabilities worse at the expense of fitness tracking and social features. In my opinion the criticism is valid. Whistle solved a dumb problem (fitness tracking for dogs) and made a dog GPS service worse.