I know it's not as cool but the Steam Deck can run HL2 at just as low power consumption with its AMD APU.

"A normal Steam Deck consumes about 4 to 7 watts of total system power when idling on the home screen with low screen brightness."

Maybe HL2 brings zero overhead to idle then?

Anyway X86 is the past, risc-v is so completely lost into eternal future... only ARM really works right now.