With budget pre builts, you’re usually sacrificing performance to an extent of cheap power supplys (that can blow up) and a tier or two lesser graphics unit for the same price as you would building it yourself.
Honestly, if you’re happy with the performance the steam deck provides then you should stick with that long enough to either realize your need for a purpose built desktop, or put it in a gen 2 steam deck down the road.
They did give out actual Gwent decks when you preordered the expansions. Idk who made them, Warner Bros I think, but they’re pretty good.