Works with a plain adapter
Nikon S sits 8.15mm further from the sensor than Fujifilm G. You need a 8.15mm adapter, but it can be a plain one — a hollow metal spacer with no glass in it. The lens still reaches infinity focus and nothing is added to the optical path.
Coverage & framing. Nikon S lenses are built for a Full frame imaging circle, which is smaller than Medium format. Expect heavy vignetting or a forced crop on a Fujifilm G body.