A:AnswerThat depends on the carrier, there is no way as of right now to purchase an unlocked 13 through bestbuy, you're better off going through apple directly to purchase an unlocked iphone 13.
A:AnswerApple made it so the only place you can get an unlocked iPhone (or at least a new one) is from them directly. The only carrier free choices are refurbished iPhones 7/8/X/XR
A:AnswerAlmost every iPhone 13 is currently backordered, meaning there's a waiting list for people to get them. We will most likely not see them available in store for a month or more.