Fallout refeence!

theres also the "bomb devil" doll from sparkle in the radiant feldspar charmony festival, which im pretty sure is a chainsaw man reference

In the Trailblaze quest "A Walk Among the Tombstones", there is a dialogue option where the main character says "I Am the Bone of My Bat. Stellaron Is My Body and Trailblaze is My Blood." Its a reference to Fate/Stay Night and Archer's Noble Phantasm "Unlimited Blade Works"

Some of the Nihility blessings in SU are references to philosophy, e.g., "Why Hasn't Everything Already Disappeared?" (Baudrillard), "Hell is Other People" (Sartre). There are probably more, but I'm not well-read enough to recognize them.

hanya let her cook achievement

Boothill's Ultimate "There's two kinds of people, my friend: Those with loaded guns and those who dig" is a line from the movie The Good, the Bad and the Ugly

One of Herta's traces is called "Fine, I'll Do It Myself" which, I think, is a reference to a Thanos quote from Avengers: Age of Ultron.

the achievement "Fate/stranger Fake" is a reference to t he Fate franchise a play on the latest animated installment, Fate/Strange Fake

The turtle in the manhole's name is Michelangelo nicknamed "Mikey". He was never called Michael.

Nah, we'd win

The Trailblazer crash in the dreamscape the same position of Yamcha die in Dragon Ball, it became a meme death position used in Naruto and other Anime/Manga

Achievement "Class-D Personnel" and "Xk-class Scenario" are both references to the SCP Foundation, that is probably the biggest collaborative writing project in the world.

Another Star Wars reference! :)

The Elation path blessing " Back to the Lighthouse" could be a reference to Virginia Woolf's " To the Lighthouse"

The Birth of Tragedy is also a honkai impact 3rd reference, it is in fact the name of a story quest in Otto's story arc. And guess what? Otto calls himself "The Fool".

The entire Aetherium Wars event is a reference to Pokemon series. My favorite part is the final battle with Hook, a reference to Gold/Silver battle againts Red in Mt Silver

you missed an easter egg to Greek and Roman mythology where one of the dialogue choices after completing the first trial is "you're making me do all the twelve labors aren't you?" The twelve labors referring to the twelve labors of Heracles/Hercules

The book March talks about in Luocha's quest, The Angler Mystery, has the same plot as Detective Conan.

The quest' name "Star's are Cold Toys" refers to a novel by Sergey Lukianenko with the identical name

One of the memory bubbles refers to several pieces of real media with altered names: "Leblanc: The Meteor Thief" (unknown), "Breaking Good" (Breaking Bad), and "Dr. Flat" (House MD)