itsjpb I would confirm the above based on actual experience with Amazon Renewed devices. It is quite difficult to get an Amazon Renewed vendor answer if the phone is BOTH "carrier unlocked" AND OEM "unlockable". Even phones sold as "brand new, unlocked cell phones" by for instance Best Buy must have "developer mode" enabled first, and then (in Developer options), be ALSO "OEM-unlocked".
It is nor a bad gambit to find someone who wants a renewed 8 (some excellent prices available!) to buy an Amazon Renewed (it will invariably be "carrier unlocked"!), and then, if it is OEM-unlockable pay that person 10% over what he paid for minimal but quick profit. (Or, you might try convincing them a different colour would better match their eyes :)