The NexStar GT mount was designed before the current line of flashable (reprogrammable) NexStar hand control technology. Because of the GT's older technology, neither one of these devices will work with the GT mount. This is true even if it is retrofitted with a flashable hand control.
The GT's menu has no GPS ON/OFF function. Even though you may be able to plug in a SkySync (or the older AUX port accessory) and connect a GPS to it, it cannot send information to the mount.
This is also true of SkyScout Connect. Even though it can be physically plugged into the GT mount, it will not work, as the mount’s technology does not have the command set to respond to SkyScout Connect.