It's not a PC it's a handheld.
It's a PC and a handheld. "Handheld" describes the formfactor, just like "desktop", "laptop" or "tablet". Or like "home consoles" and "handheld consoles".
Valve has shit support for their past hardware and maybe they'll actually try this time? Remember the steam machines? Yea most don't
Please show us the Steam machine which was sold by Valve. They haven't sold that.
But they sold Steam Link (still supported), Valve Index (still supported), Steam controllers (still supported) and Index controllers (still supported).
Every new Steam game can still be mirrored to Steam link hardware (additional to Steeam Link software solutions).
Every new Steam game with controller support can be played with the Steam controller.
Most new Steam games without controller support can still be played with the Steam controller due to community templates and flexible button+stick mappings.
Most new VR games can be played with a Valve Index VR headset and Index controllers.