No, a 3rd party app called Chiaki4Deck is adding a new renderer that will enable HDR support on the new Deck's OLED screen.

SOYJAK.PARTY/ WON

Just because you can't display HDR doesn't mean you can't take advantage of its mapping.

I had my first Chiaki4deck streaming session from my OLED and was blown away by how unnoticeable the latency and clear the image was. It literally felt like I was playing the game native to steam deck. Getting HDR support as well is going to be a real treat.