The GamePad mod for the Moto Z series of devices now has a set release date. August 25 is when the device will reach the hands of customers who have pre-ordered it, as well as when it will be available from Verizon online and retail stores.
https://www.notebookcheck.net/Gamepad-Moto-Mod-will-go-on-sale-August-25.241036.0.html