The new Nikkor Z 180-600mm f/5.6-6.3 VR lens should start shipping from B&H in the first week of August according to this Dpreview forum post. Check the lens pricing and availability at:
Previous coverage of the Nikkor Z 180-600mm f/5.6-6.3 VR lens can be found here:
Nikkor Z 180-600mm f/5.6-6.3 VR vs. Nikkor Z 100-400mm f/4.5-5.6 VR S specifications comparison
Nikkor Z 70-180mm f/2.8 and 180-600mm f/5.6-6.3 VR lenses additional coverage
First Nikkor Z 70-180mm f/2.8 and 180-600mm f/5.6-6.3 VR lens reviews