6 hours ago6 hr I believe it's Moana because the flower-like flame patterns that appear when Sora strikes something with the keyblade resemble frangipani/plumeria which grow in Polynesia and baby Moana wears one of these flowers in her hair. Also the keyblade has a lava and water theme. Moana's name means "ocean" and she journeys across the ocean to help Maui defeat a lava monster. Lastly, when I zoomed in on a screenshot that showed the keychain pendant it appears to be a tribal mask with glowing eyes. Admittedly this would fit Atlantis even more than Moana but combined with the aforementioned details I still think Moana is more likely. The blue crystal effects feel less like Moana though. They look like something from Frozen 2. Maybe KH4 allows you to combine different keyblades together?
What world do you think Sora's new keyblade is from?