not hard at all, one of my friends ordered one from amazon.ca about 3 weaks ago and it was running 4.10 and is now hacked, but ive read month ago other people getting patched units so i feel for some its just luck of the draw and did these big retailers pull from a old pallet or a newer one.
in meat-space i know i went to a walmart last week and on the bottom shelf there was still a unsold splatoon 2 bundle, so i think it really comes down to where you are and luck but its not much of a gamble because stores have return policies so you can just keep trying till you win.