There's around 110 Pals (with some sub-variant pals) on release, with more Pals to be added during early access, and after release - same with locations, gameplay, etc, they plan on continuously updating the game, and are even taking gameplay suggestions from the community. Normally, I would disregard this, but after following Craftopia for years, I can believe it - they have an update cadence of around 1-2 months or so per major content update, but that could differ with Palworld, doubly so with its rising popularity
Sub-variant Pals are "habitat unknown", incredibly rare spawns, the "chase content" for those waiting between updates; get a "shiny" variant with perfect genetics, as an example for someone like Kaela to achieve
Kirsche has played 50+ hours and only has about half of the Pals, and still hasn't fully explored the overworld because she's constantly distracted