A few Microsoft Xbox Series X and S users have noticed that the company has started testing Dolby Vision HDR gaming through the latest Xbox Insider Alpha ring release (2104). It's only available for a few games right now, including Borderlands 3, Halo: Master Chief Collection, Wreckfest, and Gears 5. The testers claim Dolby's picture quality is more "refined" than the usual HDR10, which is likely because of the dynamic data that adjust HDR visuals frame-by-frame.
Microsoft plans to release it to the general public "soon," but it hasn't committed beyond saying it will come out sometime this year. For Dolby Vision to work, you'll need a compatible TV.
Source: Engadget