Hansa and Gretyl and Piece of Shit

OK so there is a lot happening here I have no idea about.
For a start the title?? The name of the main character if Gretyl, her eldest sister is Hansa, and her middle sisters name is Piece of Shit... why?
And the play on Hansel and Grettel - yes she drops a trail of things as she walks int the forest.
But beyond that, I don't get it...

No clues from other reviewers... so I resorted to asking all-knowing karen.
Her words: “it's just a contemporary fairy tale with all the parental neglect you usually find in fairy tales, and a deus ex machina with fine print, which is also a fairytale staple.

I'm gonna have to throw two, confused, stars at this.

https://www.newyorker.com/magazine/2020/11/16/hansa-and-gretyl-and-piece-of-shit