Level Up & OSR Enthusiast
I think @Hussar was just trying to be cute.Sure they do. Krynnspace has one (Zivilyn, size class F air body), Greyspace has two (Edill and Gnibile, both size class G air bodies, the latter explicitly called a "gas giant" on p. 91 of the original boxed set's Lorebook of the Void), and Realmspace has one (Coliar, size class G air body, also explicitly called a "gas giant", same work, p.94).
I mean, sure, you can do whatever you want in your campaign. But both the example systems and the usual systems generated by the original boxed set's generation system look a lot more like the modern understanding of the Solar System than you're suggesting. It supports weird systems (and it also does things like having the "gas giants" be breathable air at standard pressure through-and-through, or Oerth be the center of its system orbited by its sun), but the really weird systems with giant beetles pushing things around, while allowed for, weren't the default.