This is a Voigtlander 10mm. It is the widest, rectilinear, non fisheye, full frame lens available. I use this on my Sony A7II. I don't know if they make a Nikon mount, but adapters are probably available.
The lowest Nikon lens for FX is the 14MM.
AF Nikkor 14mm f/2.8D ED from Nikon...