Naruto: Justice at My Back

Beck Lynn is a rear admiral in the world of One Piece. After encountering the Rainbow Mist during a battle with Blackbeard on the Grand Line, he travels through time and space to Sunagakure. Drawing on memories of his training in a previous life and combining them with ninjutsu, he develops Chakra Threads, swordsmanship, and the Six Powers, leaving a new legend in the ninja world.

This is not an invincible-protagonist story, and the main character is not a transmigrator. It is the story of someone from the world of One Piece in another world.