192 pages yes, but add 14 more pages free and however more pages the prelude adventure is as free, plus any other Monstrous Compendium volumes that support Spelljammer (might not be any).
Seems to me that they cut some of the monsters and the low-level intro adventure out of the books to save time and to keep the adventure and monster books balanced at 64 pages (while the Player/DM Setting Guide more easily fit the 64 pages).
Rather than printing these "cut pages" and separately giving them as free or low-priced charity offerings on DM's Guild, they're just giving them as free offerings as incentives to join their new platform.
Meanwhile the Dragonlance box set is the mass-combat rules for D&D, but set during the War of the Lance, while the adventure is probably akin to Wild Beyond the Witchlight or Strixhaven: Curriculum of Chaos - a few player options that fit the setting but then otherwise being the Fall '22 adventure path / AL Season (in that sense, it's kinda like how Curse of Strahd took us out of the Realms for Season 4).