For the streaming issue. Turn off hardware decoding on your Deck remote play settings.
Don’t know about the graininess. I have the etched one and everything looks crisp and amazing.
This probably opens a whole world of complex logistics Valve is not prepared/care for.
It sucks, but this is the reality of every electronic ever. You can always sell yours on eBay. Decks sells pretty fast over there.
You can also wait for the SteamDeck 2 if you don’t want to contribute to waste.
Ori will of the wisps is impressive with HDR on.