He might be really confused at first. Naruto is from a world of ninjas and chakra, while the Potterverse has magic wands and spells. He could try to use his ninja skills there and end up causing chaos as people don't understand what he's doing.
Naruto's physical abilities like his speed and strength from being a ninja would be very different from the magical abilities in the Potterverse. For example, he can move very fast without the need for a broomstick like wizards use for flying.
Well, he might use his ninja skills to become a hero in that world. He could teach the locals about chakra and how to fight like a shinobi. Maybe he'd make new friends and form a team to face the challenges there.
When Harry is summoned by Naruto fanfiction, it's likely that he would be a fish out of water. He would encounter characters like Naruto, Sasuke, and Sakura. His magic skills could be seen as a new form of power in that world. He might get involved in the battles between the ninja villages, using his own unique abilities to help or cause chaos, depending on how the story is written.
In a 'naruto gets captured' fanfiction, he might be tortured for information. His captors could be after the secrets of his Nine - Tails chakra. They may try to use him as a bargaining chip against Konoha.
Well, Naruto could gain the ability to use Kamui and use it for various things. Maybe he'd use it to surprise his enemies in battle, suddenly disappearing and reappearing in unexpected places. He could also use it to rescue comrades who are in dangerous situations that are hard to reach normally.
One possibility is that Naruto discovers a new level of relaxation he didn't know before. He's always on the go as a ninja, so the massage might open his eyes to the importance of taking a break.
Imagine if the tanto was a gift from a mysterious stranger. This stranger could be an ally or an enemy in disguise. Naruto would be suspicious but also intrigued. As he tries to figure out the stranger's motives, he also has to deal with the tanto's unique abilities. Maybe the tanto can transform into different shapes, and Naruto has to learn how to control this transformation in the heat of battle.
He would probably face a lot of challenges at first. Since he's been neglected, he might not have the proper training to handle the Zanpakuto right away. But as he learns, he could start to gain respect from those who once neglected him. His new power would change the way people view him in the Naruto universe.
In this fanfiction, Naruto might have an interesting adventure with the Twi'lek. Maybe the Twi'lek has some unique abilities that can help Naruto in his quests. For example, the Twi'lek could be very good at stealth and help Naruto infiltrate an enemy base. Or perhaps the Twi'lek has knowledge of a rare form of jutsu that Naruto has never heard of and can teach him, expanding his skills as a ninja.
Well, Naruto might use the Keyblade to gain power and respect. He could start training with it and show those who neglected him what he's capable of.