That may be a better question for the Air NZ forum. You might want to play around searching via the Aeroplan or United websites to see what award availability they see since Air NZ is unlikely to release more availability to VS than alliance partners so this is a quick sanity check on what you can expect if you call in to VS. A quick search with the United website show precious little availability for even one award seat (searched a few random weeks in 2023) though it would be worth checking more than one Star Alliance partner in case there are issues with award availability showing with a particular partner.