This doesn’t seem to be for a handheld though. The addition of HDMI CEC and the high TDP suggests this seems to be a console of sorts.
Ah, yeah, probably some console flavor of steam machine then. What TDP does this one have?
Edit: similar dev boards have been spotted with HS and U laptop chips, as well as Zen3 embedded <~55W so … it could be anything. Valve probably won’t be using an off the shelf SoC, it’ll be another GPU heavy custom job unless this is purely a dev platform or something.