Okay, so I asked oomf if I could share it and here it is (sorry I promised it last night in my time but forgor because I was trying to reverse search the reference images I used for Alchemist's Dolls' outfits and compiling them.
(Credits to Choco aka @/chococinnaMORON on twitter. Ily Chococchi /platonically)
Izumi may not be in the illust, but that alone gave me an idea for what Nozomi's character will do to Mille in their musical!
Natsume's outfit is mainly based on Anaxagoras from Honkai Star Rail + Shellin Burgundy (didn't know him prior to seeing his design). There was a fanart of him that I really liked but couldn't use because I'm still finding the artist that drew it.
HiMERU's outfit is mainly based on this
Nozomi's outfit is based on this humanized version of Espresso Cookie from Cookie Run Kingdom (I don't play the game since I heard stuff about it).
Izumi, Kaoru & Mayoi's outfits are based on these three respectively. Anyway, #CurseSphereCoordinationLimitations I'm probably one of the few people that want more stuff in Sphere Coordination.