Damn
Your theory is becoming more possible than ever
How did you even notice it in the first place
I simply connected so many Clues that indicate Final Villain is a God with Storm & Whirlpool Powers who also have Knowledge about Fate.
Oda literally Teased him in every single Arc since First Volume.
I didn't think He was Caribou's Boss, but after seeing how Oda is expanding Caribou's Role & made him also hear about Pluton & then brought him to Vegapunk's Island (Where i always guessed that's where Final Villain will be Introduced), i thought He definitely must be related to this Lurking Legend (Hence why He is taking too long to reveal Caribou's Boss)
So i checked his Introduction & Oda did draw him Praying to some God, that's when i thought it's definitely him, must be.
This Lurking Legend's Name could possibly be the same as Name of OP's Earth, just like Gorosei & Ancient Weapons are Named after Planets.
While Imu's Name is reference to OP's Moon
So Lurking Legend is Earth, Imu is Moon (Both Sides), Gorosei are Ancient Planets