It could be about Naruto somehow ending up in Moana's world. Maybe he uses his ninja skills to help Moana on her journey to save her island. For example, Naruto could use his shadow clone jutsu to do multiple tasks at once like helping to repair damaged parts of the island while Moana focuses on finding the heart of Te Fiti.
A possible crossover could involve a shared enemy. Picture a dark force threatening both the ninja world of Naruto and Moana's ocean - based realm. Naruto and Moana team up. Moana with her knowledge of the ocean and Naruto with his combat skills. They might have to combine their different forms of magic or power, like Naruto's chakra and Moana's connection to the ocean spirits, to defeat this common foe.