You never know, the Big Apple is a weird place for scavenger hunts. I would not go looking for anything in certain areas of the Bronx, Queens or most of NYC for that matter, especially in the winter. Central Park would be okay-ish though (still maybe not so much in winter). Hopefully there will be scavenger hunts integrated into physical retail stores or other indoor locations..
Anaheim CA, however, is an intriguing location for scavenger hunts IMO Disneyland, Disney Park (or whatever it is called) is located there. There I could see some scavenger hunting going on as Disneyland (like all parts of the Disney empire) love to sell chit to it's visitors/die-hard fans. What better way to herd your park visitors around with the hopes of getting something for free when, in reality, they will probably be led to areas where they can buy what they were hoping to find. I mean, the kids won't let up until parents pay up. My kids wouldn't at least.