One idea could be a crossover where Naruto characters visit the world of Maken Ki. For example, Naruto and his friends could be on a mission that accidentally transports them to the Maken Ki universe. They might have to team up with the Maken Ki characters to face a common enemy that threatens both worlds.
In some fanfictions, Naruto might be able to use Ki by undergoing special training. Maybe he meets a mentor who teaches him the ways of Ki manipulation. This mentor could be from a different realm or have a unique connection to Naruto's own chakra system, and through intense practice and spiritual growth, Naruto gradually masters the use of Ki.
Yes, in some fanfictions Naruto can be depicted as having God Ki. Writers often like to give their own unique twists to characters, and giving Naruto God Ki is a way to enhance his power and make him even more extraordinary in the fan - created storylines.
Naruto could use Ki to enhance his sensory abilities. In the Naruto universe, he already has good sensory skills with his chakra. But by adding Ki into the mix, he could expand his range of detection even further. He could sense enemies from much greater distances or even detect hidden traps or secrets in the environment around him.
There might be a mentor - like figure who helps the main character in their ki - mastering journey. This character could be someone with deep knowledge of both Naruto's world and the concept of ki, perhaps an old hermit or a powerful but reclusive ninja.
One effect is increased power. Naruto can become extremely strong and defeat powerful foes more easily. For example, he could take on enemies that were previously unbeatable in the original Naruto story.
Naruto is obviously a very popular character in these fanfictions as the series is named after him. He is often the central figure in stories that involve Ki. Another popular character is Sasuke. His natural talent and brooding nature make him a great candidate to either be an ally or a rival in stories that incorporate Ki. Kakashi is also popular, as his wisdom and experience can be used to guide characters in understanding and using Ki.
In a great deal of Naruto fanfiction, Naruto is indeed born in Uzumaki. This can add depth to his character as the Uzumaki clan has a rich history and unique abilities. Writers may use this to create stories where Naruto discovers his true Uzumaki potential earlier, perhaps having access to powerful sealing techniques from a young age, which could completely change the course of his life and the story as a whole.
In some fanfictions, if Naruto was born in Ame, he might have a very different upbringing. He could be exposed to the harsh environment and unique culture of Ame from the start. This might make him more cynical or street - smart compared to his original self in Konoha.
Yes, in fanfiction, anything can be possible. Writers can create alternate universes where Naruto is born in Kumo instead of Konoha. They can come up with various reasons for this change, like a mission that led his parents to Kumo before his birth or some sort of political arrangement.