It would be interesting if there was a one piece adventure game in which you build your own character and set out to sea to become a pirate or marine and could forge your own path gain more notoriety and getting stronger, starting out weak and getting gradually stronger,learning haki, and finding your own devil fruit, etc.
Play roblox Lol Its not good But its also not bad It has ALOT of one piece games and the same as you said You start your own adventure Learn haki and buy swords Learn fighting styles Travel Find devil fruits And alot more stuff Honestly i think you would like it