How could you split out steam deck revenue from PC revenue? If I buy a $30 game on steam, is that $30 for PC or for the steam deck/handheld? Or does it get split between the two based on how hours I play on PC vs steam deck (and how would that work if I never actually play the game)?

Personally I don’t think it’s worth having a handheld category at all. If I bought a Gameboy game for $30 but I actually played it on a super Gameboy instead of a Gameboy then it’s not technically handheld either. Just call the Gameboy a console and the steam deck a PC.