The Dx mirrorless Zfc z50 etc score a similar pixelcount compared to their larger ff Z mounts!
Nikon cameras with the highest pixel pitch are, respectively:
Nikon 1J5 (Pixel Pitch 422 pix/mm, same Pixel count as D500 and Z50, and D6)
Nikon 1J4 and 1V3 (pixel Pitch 396 pix/mm)
This is due to the CX sensor, which is only 13.2x8.8 mm²; crop factor is 2.7x, with respect to DX (1.5X) relative to a full frame.
The FOV of a 500mm on a 1V3 is the same as a 1350mm on a FF camera.
By comparison, Nikon D850 and Z7-Z9-Z8 have a pixel pitch of only 229 pix/mm
D500 and Z50-Zfc have a pixel pitch of 236 pix/mm
I use a 1V3 for astro photography: the Moon fills the 1V3 frame completely with a 500mm lens +TC1.4
Ciao from Massimo