Currently there are 15 native Telephoto Prime lenses for Samsung GX-10 and 9 of these lenses are autofocus (AF) type.
GX-10 also has a sensor based image stabilization system which means that all of these lenses will be stabilized when used on GX-10.
Since Samsung GX-10 has environmental sealings (Weather Sealing), you may like to couple your camera with one of these 3 Telephoto Prime lenses with Weather Sealings.