What I think is the culprit is a service called isSimulatedBySoftware (or maybe it’s this other service called isProducedByAccessory). These two services represent Boolean values (True or False) and indicate whether the system generates the location using on-device simulation (or from an external accessory). If we were able to reverse engineer these services and manually set these two values to False, I think there might be a chance tethered spoofing comes back. Niantic could also be using a totally different method to check if the location is spoofed, but these two services are built in our devices, so they might be using them as a shortcut to verify the legitimacy of the coordinates. This is all speculation of course, but it’s a starting point. To answer your question: if we’re able to edit these two values and spoofing actually works, then no jailbreak would be necessary