My Recommendations for a Core Nikon Mirrorless System, Some with Deals
See my Nikon mirrorless wishlist.
Top notch gear for Nikon below.
These DSLR lenses can be shot on the Nikon Z7 with the Nikon FTZ lens adapter. I recommend goimg with the Nikon Z7 versus the Nikon D850 at this point, unless the goal is shooting only DSLR lenses.
The Sigma 28mm f/1.4 DG HSM Art is a stronger lens than the Nikon AF-S 28mm f/1.4E but a chore to carry. The Nikon 28mm is much more manageable in size and weight, and has a very nice rendering style. Ditto for the Nikon AF-S 105mm f/1.4E vs the Sigma 105mm f/1.4 DG HSM Art.