Hmm.
Having used the Steam Deck for a good while - I'm not sure GPU power would be at the top of my list.
Sure, more would be better, but if I think of the entire package - right now the biggest complaint I have about my Steam Deck is the fact that it can maybe get 90 minutes of battery life if it's playing something substantial, and my #2 complaint would be that it can get pretty warm and/or noisy while doing so. That's just how much the already meager GPU eats... putting more GPU in there, without addressing that, only makes the #1 and #2 problems that much worse.
I think with respect to where the tech is - the handhelds are striking a pretty good balance between speed and portability. After all, if you didn't care about portability at all, then you'd just be on your desktop.