I've not seen her episodes in particular yet, but from what little i've seen (gifs, screens, bulbapedia summaryetc) she seems in line with game Lusamine... before her reveal of being crazy. Smothering Lillie, being obsessed with cuteness, the traits are there.
There's a major issue with this though, and it's the fact that in the game, Lusamine is actually very hateful (sort of) toward both her sons since they both ran away from home stealing a (pretty important) Pokemon and denying even the fact that Lusamine is their mother (and hiding it until it's necessary to reveal).
Lylie and Lusamine being on (at least apparent) good terms implies a huge difference in the situation, but then, Anime Lylie is already giving in to Pokemon and starting to develop a liking for them and training, very fitting with the USUM theme which suggested that Lylie will get in her "Z-powered form" waaaay sooner than in S/M.
My expectation for Lusamine in USUM is that she's not the bad guy, and the Aether foundation actually has good intentions in whatever they are doing.
This however does not exclude that in somewhat similar fashion to, say, ORAS captains, they are doing something for a good purpose (like, researching Ultrarifts for actual science) and do a terrible mistake and unleash a disastercrozma over Alola.
I have no idea in this scenario why Lylie would have Nebby with her, though. If I remember correctly, it was shown in one of the trailer that Lylie is met on same way (Cosmog on bridge), so we don't know if she *still* stole Nebby from Lusamine, or was entrusted with it, or just met it completely outside of Aether foundation.
Time will tell, USUM draws near.