If I understand your questions, any apple juice/cider can be used to make hard cider. You only need to make sure the product has been pasteurized to kill any yeast that may be present. If it has not been pasteurized, boiling would surely serve that purpose.
As far as boiling after pasteurization, my guess is that by boiling and reducing the apple juice/cider, the sugars would get concentrated by evaporating off the water. This would aid to a higher degree of alcohol when its fermented. Once it’s fermented, it becomes “hard cider”.