ILC camera bodies are exactly like operating systems. They are totally useless alone. All the value comes from applications which are available on any given operating system or in this case lenses and other accessories. Nikon really sucks here because they were the last one to enter mirrorless FF bandwagon and their Z-mount lens portfolio is extremely limited compared to pretty much any competitor.I say Nikon may have been too late with the Z series because the company is already in financial trouble. And, even if the system sells reasonably well, it's a much smaller pie these days than even five years ago.
This is the real problem for Nikon who should somehow find enough money, time and resources to create an entire competitive portfolio of native Z-mount lenses. And not by tomorrow. They need it by yesterday. And they must do this alone since third party lens manufacturers have already placed their bets on other horses and don't seem to be interested in supporting yet another non-compatible mount which has pretty marginal user base. Without external lens manufacturers Z-mount will have almost zero affordable FF lens options and based on some reviews I've seen, even expensive Nikon Z-mount lenses are not up to the standard expected at their price leve.
I also believe that the decision to create a mount which has the shortest flange focal lenght (16mm) makes it impossible to simply mount a new bayonet at the rear end of any existing 3rd party mirrorless FF lens which seems to be the modus operandi of Tamron, Sigma et al. Because Sony was the first to enter this market and became the 800 pound gorilla, all 3rd party designs are originally made for E-mount.
Luckily for Panny and Canon it's a simple task to replace E-mount with L-mount or RF-mount bayonet and a 2,0mm spacer because flange focal length increases from 18mm to 20mm but this is not possible if you must go from 18mm to 16mm. Optical system must be re-designed if Z-mount support is required as well.
Why bother especially if Nikon is stuck in the olde worlde and believe that they are still the 800 pound gorilla of high end lenses and not willing to even talk to external lens manufacturers.