It works on any Pi which has only 1 USB port - except for the power port. So on the various "Model A's" and on the zeros. The reason is, the Pi's SOC actually i

It works on any Pi which has only 1 USB port - except for the power port. So on the various "Model A's" and on the zeros. The reason is, the Pi's SOC actually is natively capable of USB Gadget mode, but only offers 1 USB port, and on the various B models they interpose a hub to offer more ports - but gadget mode stops working due to the hub being in between. The Pi 4 is an exception - its USB-C power port works in gadget mode too, unlike its normal USB-A ports, which do not, like all other Pis, because of said hub.