What existing elements have you expanded upon or new elements you added to the world and lore of Golarion in your games?

I know many people tend to run the APs as written, maybe with a few changes here or there. But I'm curious if anyone has tried extensive changes to the existing lore or entirely new additions to the world and lore. Perhaps for existing APs or as

For example, based on a thread I found written back in 2012 on the Paizo forums (found here https://paizo.com/threads/rzs2p9dz?Campaign-Arc-Idea-POSTSerpents-Skull-AP ), I've been playing around with using a sort of Ancient Aliens theme for the serpentfolk, where their deities are based primarily on the Sumerian/Babylonian deities (Marduk, Ishtar, Ereshkigal, Enlil, Nergal, and so on) known collectively as the Annunaki (no relation to the Annunaki creature in PF1e's Bestiary 5). I've been adapting the Serpent's Skull AP to PF2e with these changes, and incorporating things like powerful serpentine constructs (the so-called Fangs of Enlil, statblock here: https://monster.pf2.tools/v/92ZJMRbV-fang-of-enlil ) that guard the Vaults in the Darklands, where these Vaults are chambers holding Annunaki genetic experimentation laboratories. The Nephilim (the creature from PF1e's Bestiary 3) are one of the many experiments of the Annunaki.

Instead of being a post-Serpent's Skull, I'm essentially changing up Serpent's Skull to add in these elements. I really like the idea of Ancient Aliens (it's one of my favorite sci-fi tropes, mostly thanks to Stargate SG-1) and I love the serpentfolk as villains so combining the two with a dash of Babylonian mythology just felt perfect.