I am looking to add the Nikon D6 and finding it quite difficult to find one or the new Nikkor 120-300 FLED ZOOM..! Have several D5's but wanting something new..
There are some local camera shops that have a special deal with Nikon and can get a camera or lens fairly quickly. I waited 10 months for the 500mm f/5.6 PF, and then placed an order with a local shop and got it in 4 weeks. Take a look for a shop with that kind of arrangement.
Have you applied for NPS membership? You have enough top gear to qualify. It's based on points depending on the gear you have. NPS members normally get priority on new gear so the retail shop gets an additional allocation for NPS members above it's normal stock. The process is easy and good for all involved. You should be able to get the gear within 30 days or so.
I am really enjoying the 500/5.6 on the d5 right now. I had been using on the d850, but I think I get better looking results on the d5. I just got a used d5 about a week ago.