One thing I like about Z-A that in hindsight I wish Arceus had done more of is that, with the DLC, a fair chunk of the new Pokémon from Scarlet & Violet are not only included in the Pokédex expansion, but are also actively showcased through various side quests. (Not to mention, four of them even get Mega Evolutions.)
It’s something that makes Z-A feel more aesthetically of a part with Gen 9, and gives those Pokémon some more time in the limelight while their generation is still current. (Fortunately, Z-A also does this for a share of Gen 8 Pokémon as well, which kind of makes up for things.)