kingkongdf
thanks for the chapter and i would suggest you start times skips up till rogers era and with those time skips talk about the legends that the mc made and his children and some of the stuff he has been up to and just basically build him and his wife up as legendary sea kings of enormous size and power then you can really start the story and have more to work with
On the most recent chapter of one piece, there was some children, clone of the original shichibukai, they had special powers similar to devil fruits, those powers came from artificial bloodlines, Poseidon the ancient weapon that allow an individual to rule over all sea life is a blood line, to move the story forward, I recommend you to go into clan blood lines and specific abilities, you can do that to create more depth to big mon wanting to mix her bloodline with every other species capable of cross breeding, you can make so a special bloodline is needed to condense a concept into a fruit to grand a expanded set of abilities depending on who ingests the fruit, your own original origin for devil fruits in Atlantis, you can make so IM knows about this and there is something evil sealed in atlantis, but the people of atlantis gave up in fighting against this ancient evil and stop cultivating bloodlines into fruits, you can make so joy boy wants the evil to be free and be purified and IM wants the ancient evil to be eliminated, and the last island is a point of contact of Atlantis and the surface, its the place the ancient evil will go once released, and you continue the story from there, its the best i could come with in a few minutes.
Write about him trolling people. Have him be powerful enough to create a mythical devil fruit that has a fraction of his power and use it to troll. Visit zho and troll the elephant. Have him and hela shrink to human size and start an auction house with Atlantic treasures. Mind control celestial dragons and troll.
Diving deep in the lore of One Piece can be a bit challenging seeing as there's so many episodes and manga chapters to read ,Although you can cut the filler episodes and whatever else i don't think it would be easy to derive hidden lore and world history from the one piece universe, so it's okay to be creative don't stress yourself out find pieces of information and use that otherwise good story đâ¤ď¸