Yes they do sell unlocked iPhones, the only problem is that if you go with a specific carrier like Verizon you don't get the same features with an unlocked phone as a carrier-specific phone I know personally. You're better off getting a carrier-specific phone, you pay the same amount, the only difference is that your phone has to stay with that carrier.
Yes, Apple does sell unlocked iPhone 6s devices here. Just make sure you tell them that you want an unlocked phone, not a carrier specific one.
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