Currently there are 32 native Wideangle Prime lenses for Panasonic GH4 and 17 of these lenses are autofocus (AF) type.
Panasonic GH4 doesn't have a sensor based image stabilization system and none of these lenses have optical Image Stabilization.
Since Panasonic GH4 has environmental sealings (Weather Sealing), you may like to couple your camera with one of these 7 Wideangle Prime lenses with Weather Sealings.