The Final Girls is probably just an Honorable Mention as far as the GU archetype goes, but worth mentioning, as it cleverly references the old slasher movies that are often themselves Girls Underground stories. I will also note that early on, there is a mention of the Persephone myth, and GU examples often will reference other GU stories (most often Alice, but sometimes older myths and fairytales).
Max loses her mother in a car crash, and years later tries to connect with her memory by going to see a showing of the movie that made her momentarily famous, an 80’s slasher film called Camp Bloodbath. Max and her friends get magically transported into the world of the movie, complete with killer on the loose, and Max finds herself trying to rescue her “mother” (really the character played by her mother). They become the “final girls” once all of Max’s friends and the other characters are killed off. But it is only when her mother sacrifices herself that Max gains the power to defeat the adversary – which somehow magically rescues all her friends and sends them home…. or so it seems.