Don’t have any book recs, but Absolute Elsewhere is a banger.
Edit: on second thought, the Forerunner book trilogy based in the Halo universe may be worth checking out. Greg Bear is the author. The story is set wayyyy before the events of the Halo games and details the fall of the forerunners to the flood parasites. Lots of cosmic horror and concepts around creation and destruction, moral dilemmas, and not just infectious pathogens but infectious ideas.
Shadow of Intent’s album Primordial is a concept album based on these novels.