If you want to play older, lesser games with a better screen go Deck - if you want to play newer more demanding AAA’s then choose any Z1 extreme over the Deck.
Personally I’m going for the Go for the extra improvements & 2 x USB4 plus that whopping brilliant screen.
AS a side note - I’ve always loved my 512gb etched screen, never been dissatisfied apart from the size, always wished it was bigger for better reading of screen.
You’ve finally sussed how to buy games! ALWAYS give a game a year - by then bugs are fixed, updates added, price has dropped dramatically & usually “complete” can be had for much less than half the original rip off release price.
You NEVER run out of latest AAA’s - your just a year behind the curve. I’ve been doing that since the PS3 days