One Piece: I Ate the Gum-Gum Fruit and Became a Stand User

The synopsis has been changed, so I'm taking it easy right here.

The protagonist has a golden finger, but somehow doesn't entirely have one.

To grow stronger, he eats a Devil Fruit and nearly gets silenced for it.

Just when he finally thinks he's strong enough, the people he has to face are all admirals or fleet admirals.