I have an old IBM F122. A 122-key keyboard is pretty much peak keyboard when it comes to easily purchased commercial offerings. The smaller less sturdy sibling of the F122, the M122 (yes, M as in model M) can still be purchased relatively easy, but then you lose about a kilo of weight, nicer switches and N-key rollover. The prices for model F keyboards are bonkers today though.

Your option when it comes to a lot of keys (as the one posted here) is either to build it yourself or try to find some very specific offerings, maybe aimed at video production.