Since at least November it has been pretty clear that the z9 would be the most in demand camera from Nikon in years. A lot of people set their alarms to log onto B&H as close to 8:00 as possible on 10/28, based solely on specs. Most of those who didn't figured out the wait was long sought other sources rather than waiting for B&H or Adorama to get enuf stock to satisfy the demand. To me, jumping ship because one didn't get his camera when he wanted and didn't appear to do anything to move that along makes no sense, let alone blaming Nikon. It's not a mature reaction.
I, too, started getting serious in 1969 with a new Canon and 3 prime lenses. Cost $330, including the flash when a Naval officer brought it back from Japan for me. I later switched to Nikon because Canon's electronics kept breaking, then to Contax because the cheap Nikon zooms of the time weren't sharp enough. I came back to Nikon with the D2x and never looked back after Contax went out of the digital business. Nikon has been a great company to buy from, and never had a bad camera or lens thereafter [no more 43-86mm zooms for me].
Find a small retailer with an extra camera or a short waiting list, and stay with your lenses and the product you know. There is very little the z9 can do that a z7ii can't, other than that silly BIF thing, and maybe shooting some sports. There are a lot of pros not using $5500 camera bodies, and taking great images. A few months from now, you will have forgetten the whole problem - it will take that long to figure out a Sony's menus anyway.