I think Oda is hiding the heaven part of Elbaf
I think something there
Heaven World is also referred to as Astral World.
The Fabiophase of Egghead was modelled after the Ancient Kingdom, and was full of Holograms.
The "Gods" of Elbaph are real, and are remnants/descendants of Giants that survived the Void Century war by sealing themselves in Heaven/Astral World, by protecting themselves with Ancient Tech, full of Holograms and advanced weapons. Maybe Lunarians, too.
Like a knock off Valhalla (I do believe Valhalla is a real place in the One Piece afterlife, tho).
I also think the Underworld is full of Ancient Tech under the ice. Baldimore was a Winter Island, and Franky found Vegapunk's secret lab under the ice after he blew up the first one. Punk Hazard had the frozen Galley Ra Giants to begin with, and then half of it became frozen. Egghead was a winter Island before Vegapunk's Air Conditioning. Oda is very consistent with ice/Winter Islands hiding Ancient Tech.
I believe the Underworld of Elbaph was formed during the Void Century, with the ice coming from flooding, then freezing during the sun being blotted out from cloud coverage/ash. So, a lot of tech should still be under there, ancient Elbaph labs... And there's a guy on Elbaph, whose Fruit lets him naturally sense metal/electromagnetic energy
Kidd will get his tech/knowledge boost from a lab under the ice, same way Franky did.
The flooding/rain prevented the Adam Tree from dying in fire during the Void Century war, but, Elbaph's people needed to hide away from the WG/Imu. Where do you go when it's flooding?
The "Gods" of Elbaph, are overpowered Giants/other races from the Void Century that rule the Heavens World. These are the "Evil Giants" Luffy will face: if they digitized themselves/became Holograms, like the monsters in the Fabiophase on Egghead, it's entirely possible that beings FROM the Void Century still live up there, and survived by turning themselves into "data". Like how Lilith wants to restore the Stella with a Stella-Clone and Punk Records.
I believe Zunesha and Pluton also have Void Century Remnants in them, but those should be allies.
The "Gods of Elbaph" are real, from the Void Century/know of it, and are in the Astral/Heaven World. My only question is, did they betray Elbaph itself? When the flooding started, did the "Elite" of Elbaph, decide to let the "lesser Giants" (Ida foreshadowing) and "lesser races" (Rodo and Loki racism foreshadowing) drown, while they used the Ancient Tech in Heaven World to keep themselves safe?
Oda is remarkably consistent with the bad guy being at "the top": Arlong Park, with Arlong losing at the top of the building: Alabasta, with the bomb being in the clock tower, and the final fight being in Alubarna, a raised city; Enel being a God in "Upper Yard", and seeking "Fairy Vearth", the Moon above the Blue Planet; Enies Lobby's Tower of Justice; Moria's Castle; Marineford and Ace's execution stand; Dressrosa and Doffy's castle/defeat in the air; the Tea Party at the top of Whole Cake; Onigashima FLOATING IN THE FUCKING AIR; Punk Records with York/Mars; and the worst of the worst, the Celestial Dragons.
The real evil in Elbaph is at the top, in Heaven's World. There be Aryan Ass Giants up there, I'm calling it. I'm wondering if Imu directly invading their territory, might be even for Heaven World to intervene... I think Shanks/Kidd showing up to help is much more likely, though. I think Loki asked Kidd to explore the Underworld's labs (Loki should know about them due to his CoO, but can't interact with them due to size/ice/imprisonment).
Kuzan in theory could thaw the Underworld, too.
