Just popped a Voigtlander S-Heliar 50mm f3.5 "Vintage" (Nikon S mount) on the Z6 to see how it stacked up against the Nikon Nikkor-SC 5cm f1.4. From f3.5 with each lens, the Nikkor almost held it's own all the way up to f16, in the center of the image, with the S-Heliar being only slightly sharper at close distances, and a wash at infinity. But when you move away from the center of the image, the S-Heliar really outshone the Nikkor. At infinity, edge to edge sharpness with the S-Heliar was way ahead of the Nikkor from wide open with the Nikkor almost catching up by f16.
Going to be doing some landscape shots with the Z6 at the end of the month, and I'm going to go with the S-Heliar.