I think it might be a "World King" ability.
1. Joyboy seems to be the original user of The Voice of All Things.
2. Poseidon was the original user of The Voice of the Sea. Shirahoshi has this ability, now, and she used it to command the Sea Kings.
3. Pluton was the original user of The Voice of the Land. Momonosuke has this ability, now, and he used it to command Zunisha.
4. Uranus was the original user of The Voice of the Sky. Princess Vivi has this ability, now, but there has been no indication that she has it.
Some information about Nefertari Lili and how it relates to a Sky God.
In Egyptian art, Queen Nefertari is frequently depicted with Horus, the falcon-headed god. A common scene shows Horus leading Nefertari by the hand, often into the afterlife, with Osiris, the god of the underworld, also present. These depictions are found in Nefertari's tomb in the Valley of the Queens and are meant to symbolize her passage into the afterlife.
In One Piece, the Alabasta Kingdom has a "Tomb of the Kings," which is a royal tomb where members of the royal family are buried. It's located just outside Alubarna, the capital city, and is situated underground. The kingdom itself is inspired by ancient Egypt, with many architectural and cultural elements reflecting that influence.
Vivi has been compelled to fly and has demonstrated her affection for the sky before. Furthermore, she was purposefully restricted from flying on Pell's back by King Cobra.
In my own mind... all this seems to make sense. However, to anyone reading this, it probably doesn't.