Then you'll want to read Death Troopers and it's prequel Red Harvest, both by Joe Schreiber. The former is fairly standard zombies on a spaceship, the latter digs deep into the past to uncover it's origins and is much more interesting for it. The first book would make a good lower budget movie that could test the waters for an R-rated Star Wars outing and then they could go big with thr second one if there's a taste for it.
George Mann's Dark Legends is an anthology of Star Wars horror stories and his earlier Myths and Legends leans into this too.