It’ll be the cheapest place, by an absurd margin, to play Baldur’s Gate 3.
And what exactly do you consider “a great experience”? Because in act 2, with the game looking as shit as it possibly can, it still struggles to stay above 20FPS. I haven’t bothered trying act 3 on Deck, but act 3 is even more resource-intensive than act 2 so I can’t imagine it fares any better. “A great experience” is admittedly subjective, so I can’t say you haven’t had what you consider to be a great experience on Deck, but vaguely describing it as “a great experience” is negligent at best and outright disingenuous at worst. My act 2 experience on Deck was abysmal, and I think most opinions on that level of performance would agree.
For those that don’t care about Linux, or portability, or the steam deck being a PC, and just want to play BG3 on their TV for as cheap as possible, the Series S is by far the best option. That the game will also look and run significantly better than it does on steam deck is icing on the cake.