I recommend 'The Legend of Celestial Immortals'. The main character of the novel, Mo Xian, traveled to the Firmament World and became an outer disciple. He loved farming. While the various big shots were fighting over the Ginseng Fruit and Lingzhi, Mo Xian was using these precious spiritual medicines to feed sheep or rice. In the end, through their unintentional actions, all the important figures came over to beg Mo Xian to exchange for the spirit herbs. If you're interested in this novel, you're welcome to read it. I hope you'll like this fairy's recommendation.
One interesting idea could be that Luffy has to rely solely on his Haki and physical training, making him even more of a badass in combat. He might develop unique fighting styles that we haven't seen in the original story where he had devil fruit powers.
Marshal Sengoku of One Piece ate the Rock Fruit. This fruit could turn him into a stone man who was immune to physical attacks and had a certain defense and weight.
In this fanfiction, perhaps Luffy uses the Copy - Copy Fruit to copy the ability to fly from a certain character. Then he can explore new areas that were previously inaccessible. He might also use this flying ability in combination with his rubber powers to perform amazing acrobatic maneuvers during battles, making him even more unpredictable and difficult to defeat.
In fanfiction, if Luffy ate the Flame - Flame Fruit, he would gain the power of fire. His attacks could be infused with flames, making his Gum - Gum Pistol even more powerful. He could also use fire to defend himself, like creating a wall of flames around himself.
Definitely Luffy is the central character. In addition to his crew, there could be new characters created specifically for this fanfiction. Maybe there's a powerful villain who has a unique power that Luffy tries to copy. This villain would be a major character as Luffy's actions and development are centered around trying to overcome this foe and make use of the copied powers against him. There could also be a mentor - like figure who helps Luffy understand the full potential of the Copy - Copy Fruit.
"One Piece: Eating the Fruit of Hurricane at the Beginning" is a light novel written by the author, pure and bright. It is a derivative Doujinshi novel. The general plot of this novel is as follows:
Ling Feng had transmigrated to the pirate world and eaten the Nature Devil Fruit, the Hurricane Fruit. Originally, he wanted to join Luffy's Strawhat Pirates and go on an adventure together, but the system told him that he had to form his own 10-man pirate team to create his own adventure legend. Helplessly, he could only start recruiting crew members and prepare to begin his adventure.
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One Piece: Dominating the World was a light novel by the author, Peanut Hanamaki. The general plot of the novel was:
This was the world of OnePiece, sixteen years after Luffy became One Piece.
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"Starting from Luffy to Save the World" was a light novel written by the author, Aurora Scattered. The general plot of this novel was:
This was the story of a fledgling system that had been beaten up by two baldies in a row and began to kill its host, merging into one.
After losing the rubber fruit, Luffy began a brand new life with the dream of saving the world.
This book brings you into a different world of pirates.
This book was also known as "The Adventurous Journey of Luffy with Online Intelligence","The Strongest Tool Man Sauron Training Plan","How to Abduct Nami Directly","The Beginning of the Monchi D Family's Glory", and so on.
[PS: Momosuke must die group chat: 1042476737]
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One Piece: The Full Member System was a light novel, a derivative doujinshi novel, written by the author, Wu Shiyi. The general plot of the novel was:
Momosuke must die. [Inscription: Luffy, the protagonist who accidentally transmigrated into One Piece, awakens a strange system partner. Only when he becomes stronger can I become stronger!] Caught the wild Roro Noya Sauron, reward: a knife. From then on, there were Dragon Destroyer Mages, Psychics, Pengri Ring users, Food Hunters…My comrades! Let this world feel fear! P.S.: Welcome to the modified One Piece World. Group chats number: 534403868.
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One Piece: Tricking Luffy into Joining the Army, Changing the Plot to Become Stronger was a manga novel written by the author. The general plot of the novel was:
He had transmigrated to the world of One Piece, and before the plot had even begun, the rebellious system had awakened."I want to become a navy general!" [Congratulations on changing Luffy's ambition and making him work hard to become a navy general. You have received 2,000,000 Rebel Points.] [Congratulations on successfully instigating the Yellow Ape to defect. Reward: Natural Fruit…Congratulations on obtaining the Dark Fruit.] As long as you change the plot, you can become stronger! The world of pirates will be completely rewritten by me!
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"The Fourth Calamity of One Piece" was a light novel by the author, Carefree Ninth Master. The general plot of this novel was:
The new book has been released-Ninja in One Piece... Volume 1 ~ Volume 3, Volume 4, Volume 5... It was decided at the last minute that it would be a player-oriented manga, and One Piece would be longer. Group: 645200189.
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The Descent of the Devil's Fruit, The World of the First Generation of Pirates was a sci-fi futuristic novel written by the author, Zhao Zui. The general plot of this novel was:
As the Demon Fruit descended on the Blue Planet, Oda admitted that he was a Prophecy Fruit user. On the other hand, One Piece was merely an adaptation of the scenes that he had predicted. In the manga, the demon fruit tree had already begun to wither, and the world of pirates was nearing its end. You couldn't imagine how many Devil Fruits had been drowned by the tide of history. You wouldn't be able to guess how terrifying the world of the first generation pirates was. The owner of the Money Fruit was a cheater. I'll let you know what it means to do whatever you want with money. The owner of the Gambling Fruit was known as the strongest. No one in the world was willing to offend him because he dared to bet his life with you. The Time Fruit and the Space Fruit were weak in front of the owner of the Reincarnation Fruit. However, he could only leave in regret. Before he left, he left these words behind. "I might not be as good as you in this era, but I will still exist in the next era." Guess who wrote the Demon Fruit Atlas, and guess what kind of fruit the protagonist needs to compete in this world. How did the Heavenly Dragon people get their title? What's the strongest weapon you've ever seen? Supreme Swift Blade? If you use the fruit juice of the devil fruit as a quenching agent, guess what will happen. Welcome to the world of the first generation of pirates. Here is the answer you want.
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One Piece: The Demonic Epic was a light novel by the author, Crimson198. The general plot of the novel was as follows:
How did the Demon Fruit form?
Why was Hai Loushi able to restrain the fruit's ability?
Why were the D-Clans so powerful?
…
This was a battle between D and the planet's will! All the mysteries of the sea originated from this.
Ever since the era of pirates began, the entire world had accelerated towards doomsday.
If Luffy reached the top, the world would be doomed!
"What will you do?"
Kelan Lyn was at a loss."…Is there a way to escape?"
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One Piece: Caesar was a light novel written by the author, Fallen Light. The general plot of the novel was:
His soul transmigrated to the pirate world and became Caesar Kurang. The future timeline that the protagonist could know was until Luffy completely defeated "Hundred Beasts" Kaido. A dual fruit aptitude user, transforming into a giant dragon. [Momosuke must die. Keyword: One Piece, Caesar, Dragon, Twin Fruits, Hegemony, Decisive Killing, Ambitionist.]
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A Journey to the Worlds Starting from One Piece was a light novel by the oldest author, Gu Gu. The general plot of the novel was:
At the beginning, he passed through One Piece.
This was the story of the Pirate King who began to roam the myriad worlds and roam the heavens.
[Current status: One Piece (Hot Series)-To be determined-]
[PS: The introduction is too weak, please move to the main text!]