Maybe in the fanfiction, the Dragon Devil Fruit was created by some ancient shinobi who experimented with combining different forms of chakra and devil fruit powers from another world. Naruto discovers this fruit during one of his adventures outside of the Hidden Leaf Village. As he eats it, he has to learn to control the new powers which are very different from his normal chakra - based abilities. He might struggle at first, but eventually masters it and becomes an even more formidable ninja.
One idea could be that Naruto somehow obtains a Dragon Devil Fruit. He then gains the abilities like flying, breathing fire or some other dragon - like powers. This would completely change the dynamics of his battles in the Naruto universe. He could use his newfound flight to gain a strategic advantage over his opponents and his fire - breathing could be a powerful offensive move.
Another fanfiction concept could involve Naruto being sent to the One Piece world through some kind of strange ninja jutsu gone wrong. There, he eats a Logia Devil Fruit that allows him to turn into water. He teams up with the Straw Hat Pirates and uses his water - based powers, along with his ninja knowledge of chakra control, to help them in their adventures. For example, he could use his water form to put out fires on the ship or create water - based defenses against enemies.
Maybe in this fanfiction, there's a group of ninjas in the Pokemon world who are inspired by the ninja ways in Naruto. They strive to become Dragon Masters, using their ninja skills along with Pokemon training. A young trainer, similar to Naruto in spirit, starts with a small dragon - type Pokemon like Dratini and through many adventures and battles, they grow together to become a great Dragon Master.
One interesting idea could be that Luffy's dragon devil fruit gives him the ability to control different types of weather related to dragons, like summoning thunderstorms or creating strong winds. Another could be that he gains the power to transform into a dragon - like form with enhanced strength and speed.
Another idea is that Naruto is reborn in the High School DxD world as a half - dragon due to the influence of the Dragon God. He then has to navigate the complex social and power structures of the DxD world while also hiding his true identity at first. As he discovers more about his new powers and the world around him, he gradually becomes a key figure in the battles and politics of the DxD world.
Another concept is that Naruto is sent to Middle - earth. There, he could use his ninja skills and chakra powers. He and Gandalf could team up to fight Sauron. Naruto's ability to make friends and inspire others would be really useful in uniting the different races of Middle - earth against the common enemy.
One idea could be a crossover where Naruto characters gain the abilities of Needless characters. For example, Naruto could get the power of Adam Blade's regeneration. It would be interesting to see how he uses it in battle, especially against tough foes like Pain or Madara.
Another fanfiction concept could be that a few ninjas, including Naruto, are given the ability to transform into mini - Transformers. They could use these new forms to gain an edge in battle, combining their ninja skills with the advanced weaponry and abilities of the Transformers. This would create a whole new dynamic in the Naruto battles and introduce some really interesting fight scenes.
Another concept is that Euphemia discovers a strange portal and steps through it, ending up in the Naruto universe. There, she befriends Naruto and his friends. She could use her diplomatic skills to try and bring peace between the warring ninja clans, while also learning some ninja techniques herself.
One idea could be to have Naruto enter the world of Bloodborne. Maybe he is on a mission and accidentally gets transported there. He would have to deal with the dark and dangerous creatures using his ninja skills. His chakra could be an interesting element in this world, perhaps being mistaken for some sort of otherworldly power by the inhabitants of Bloodborne.
Maybe Naruto discovers Cortana's existence while on a mission in a strange dimension. He is intrigued by her digital form and her ability to store vast amounts of information. Cortana, in turn, is fascinated by Naruto's determination and the concept of chakra. They form an unlikely alliance to face new threats that are emerging in both their worlds.