While that comment was made as a meme, and I certainly thought of the Steam Deck, what I was initially thinking was about a super efficient SteamBoy of sorts.

An ARM-based, powerful, power-efficient, and pocketable handheld to play select retro games from Steam. And of course it will support emulation. It's just wishful thinking at this point but would be great. I think a smaller handheld would pair nicely with the Steamdeck.