Nami's importance is in the endgame. Oda has been trying to hide Zoro and Nami's backstories for as long as possible. Nami is Uranus, and connected heavily to the moon. That's why she's always referenced along with the sky, and is able to intrinsically understand and in some cases control the weather. She is the Goddess who controls the skies, Uranus.
Her Wano/Elbaf power up should involved her using Sky Clouds, tying back to Skypiea and her using the Waver. Sky Clouds can be used as shields, weapons, platform, rails for movement: combined with her electric attacks, end-game Nami should be pretty fucking powerful.
@AverageNamiEnjoyer