I loved my steak deck, but I sold it and got a ROG Ally, it's better in every way and makes me wonder why Valve is just letting other companies run away with their idea.
What do you mean by Valve's idea? Gaming oriented ultra mobile PCs existed before the deck. Valve just brought us an affordable one. (That runs Linux. Plus all the resources they put into proton.)
Edit: You can go back to at least 2010 with the Pandora.
Valve has said, with pretty much every hardware initiative they've ever had, that their goal was to create a product line that other people will start competing with. They want to push the handheld form factor PC because they know it opens up a new group of gamers to their platform. They don't care who is making the hardware.