The Z80K and the Z80320 where not really marketed in North America, but these chips did make it into some systems out side of North America. Mostly Latin America and some Asian countries. Zilog omitted some of the signal pins and deleted some of the 16-bit version instructions which lead customers to use the hybrid Hitachi OEM, NEC OEM versions. If not you need the 3Rd parity fix chip to solve these bugs.
There is another website that starts with a F that has some of them listed, but I forget who it was.
Yes there was some Aerospace/Avionics that do have those chips in them. (mostly Mil. Std related devices). Their also is some suppliers that still have them listed as available, but just
forget about because they are all reserved. You could check out
https://planetonecomponents.com/index_about_en.phtml and search for Z8070, Z80000, Z80320 and find its 8MHZ and 10MHz version listed. But with a out a active (military) cage code and Government related Po to prove your order is ujit plus a hole lot of funds you wont be able to get any.
By the way some Mil. Defense Suppliers back in the 2000 where charging 6k pre 32-bit Z8000 chip in US funds.