I now see the contours of a complete lens line-up for my Z6 using the "ancient" RF Nikkors ('S' mount) and equivalents. the latter being of course more modern developments made by Cosina/Voigtländer in the mid 'naughties (approx. 2005). Using the Roxsen N(RF)-Z adapter or a dummy F-Z (for the 15mm Heliar), the focal length ranges covered in the shot below are 15 to 105mm. It should be evident these lenses are surprisingly petite even with their adapters added. They are a lot of fun to use on the Z cameras and results are surprisingly good too.
Lenses depicted here are Voigtländer 15mm f/4.5 Heliar (F mount), Voigtländer 21mm f/4 SC Skopar (RF mount), 3.5cm f/1.8 W-Nikkor, 50mm f/1.4 Nikkor 'New Olympia' (in a focusing DIY mount), Voigtländer 50mm f/1.5 Nokton (RF mount), 8.5cm f/2 Nikkor (RF, the legendary Nikkor) on the Z6, 10.5cm f/2.5 Nikkor ('Sonnar' type). I do have some of the longer RF Nikkors such as the 25cm f/4 and 35cm f/4.5 as well, plus the 13.5cm f/4 Bellows-Nikkor. I also have a nice black 13.5cm f/3.5 Nikkor RF.
Nikon enthusiasts will note this particular 8.5cm Nikkor is the rarer Contax version as indicated by the 'C' engraved on the focusing barrel, but of course this has no significance on the Z camera with its visual focusing.