I initially thought there might be some sort of licensing/exclusivity deal involving the NHL, Adidas and/or Fanatics. However, Vancouver has sold their speciality warmup jerseys, albeit at a staggering cost of $750 each:
https://vancouver.citynews.ca/2023/0...jersey-prices/
As for actually wearing them in games, I understand that is tightly controlled by the league; you're not allowed to just wear whatever you want.