I'm quite surprised Silvally made it into the dex. Does that mean we'll see Gladion or someone from the Aether Foundation? If I recall right, there should be 2-3 Type:Null in the lab, so it would make sense if one of them were given to you because Pkm usually don't like to stay in a place, and I bet you're quite "gifted" at befriending Pkm.
That aside, I'm sad Starmie didn't make it, and it seems the dex ends with 400 + possibly 1-2 new Pkm, probably a mythical. That's roughly one hundred more Pkm than SM's regional dex, I believe. It is still possible we'll get a chance to catch other Pkm, but as in SM and USUM, they won't be registered in the dex.
As for the choice of Pkm, I hoped that Xatu would get a chance to shine, but if there's Sigilyph, that won't be easy at all. Same with Golisopod and Araquanid, the latter being more useful as it doesn't have a hindering ability. However, there's a chance Xatu and Golisopod get some chances to shine through buffs, new moves, etc. So, I'll wait.
Galarian Yamask is cool, its new mid-evolution (?) as well. Or could that be just a split evolution? No idea.
Then, it seems we won't get any sub legendary Pkm. I'm actually fine with that if this is true because I always wanted to know how a metagame would look like without legendary Pkm, not that I'm against them, but come on, if we're in the Pkm world, it's highly unlikely for a trainer to have legendary Pkm. It could give some Pkm more of a chance to shine.