The Xbox One is (essentially) using an AMD HD 7790, which AMD [1] have confirmed to support DX 12, and Microsoft have confirmed that DX 12 is coming to the Xbox One with the Windows 10 update [2].
"Any" console supports the important features of DX12. The functional additions to DX12 are few and those would likely be exclusive to PC until the next console iteration. The significantly more important low-level API has been in consoles since day 1.
The lack of a low-level API on PC is why bad console ports have happened in the past - so there's your citation: every bad console port ever.
It certainly doesn't literally run Windows for games. The Xbox One is a hypervisor based system where a Windows 8 based OS is used for utility applications and user interface, but a custom OS is used for the games[1]. The believe the latter has as much in common with Windows as the Xbox 360 OS (not a huge amount).