The current implant chips are not nearly complex enough to generate a radio signal that can be tracked, let alone produce GPS data. It is just like a barcode under the skin, it can only produce a number when scanned.
This is true. Whoever is talking about GPS is just plain wrong. GPS devices need a power supply. Just like your phone, your car navigator, etc. They need to be charged every day.
That said, I am wholeheartedly against any implantable device, even if it is just a passive one used for scanning my ID.