It's a good book, but I didn't feel fangirly about it at all. Apparently, I'm not the only one. I've checked AO3 out of curiosity and there's no fic for it. For comparison, All for the Game has more than 4500 fics, which is very impressive for a book fandom. Basically, this post is a rec for AftG and not for Elysium. XD
In terms of diversity, Elysium has a Black female protagonist and minor m/m. The female ghost is probably queer too.