My wife and I are currently on Sprint, but are considering a move to another carrier. I'd like to upgrade soon and am looking into getting a device that I could take with me from Sprint to whatever other carrier we choose. I know the Nexus 6P and Pixel devices will work on any major carrier....but other than the Nexus devices and the Pixels, are there any other phones out there are considered "Universal Unlocked" here in the US?