Steam Deck, hardwarewise, doesn't even really matter that much to Valve anyway. It's all about the universal deployment of Steam through Linux and Windows and the amount of money that will potentially rake in.

Right now Microsoft, through the Xbox Play Anywhere strategy, and Sony, to a certain degree*, but especially Microsoft is _exactly_ doing what Valve wants and supporting Valve in what they want: get Steam deployed in as many households as possible in as many form factors as possible.

It never was about the hardware, but all about the service. You'll see.

*) By allowing previously Playstation exclusives onto Steam, which means that when you have a Steam compatible device you can play all the Xbox, Playstation and PC games you want. As an example, Stellar Blade -one of the best selling Playstation exclusives last year- will be released on Steam in a few days.