Currently there are 32 native Wideangle Prime lenses for Sony A6400 and 18 of these lenses are autofocus (AF) type.
Sony A6400 doesn't have a sensor based image stabilization system but 1 of these Wideangle Prime lenses features optical image stabilization.
Since Sony A6400 has environmental sealings (Weather Sealing), you may like to couple your camera with one of these 9 Wideangle Prime lenses with Weather Sealings.