Happy it helps - I’m a big Hellboy (and occult detective, in general) fan, so am always on the lookout for other things that would scratch that it itch and those are the ones that came immediately to mind. It’s a lot so have a read around and see what sounds good. If I had to grab a couple of books off the shelf to get you started then I’d go The Doom That Came to Gotham (recently got a nice trade I believe) and either Hellblazer or Necronauts.

Worth noting a number are from 2000AD, so you’d largely get trade paperbacks collecting the original anthologised stories, but that might not be an issue coming from Hellboy where you really get a collection of shorter stories.