I think the closest thing that exists currently in PF2e official APs would be Blood Lords. I haven't played it, so I don't know how close to gothic horror it is, but it's the only really undead-themed one out right now.
There is also Malevolence and Night of the Grey Death, which are both horror themed. Based on the descriptions, Malevolence is more haunted house themed and Grey Death is more culty-themed. I haven't played either of these as well.
You might also look at the case files in Dark Archives; while not a full blown adventure path, they do hit on more of that Cthulu-esque dark fantasy.