For 20 years many have tried to figure out what One Piece treasure is and it might’ve not been as in your face as you thought it was, at least not until chapter 1044 when we first get introduced to the drums of liberation by Zunesha.
That’s right, the treasure is… Joyboy’s Drum.
I came to this conclusion after researching who Joyboy is based off of which is Shiva from Hindu mythology, and he carried a drum called Damaru with him, and played for his son Ganesha. Ganesha? Does it sound familiar? If you thought of Zunesha, you are correct.
Also, the person who made the language known as Sanskrit saw Shiva play the drums in his dream and he made the language based off the sound that came from the drum. Could that be how Poneglyphs are made? “We are the ones who weave history with the sound of the grand belfry”. Maybe Poneglyphs are just a song, who knows.
Moreover, Joyboy and Zunesha oddly enough parallel Brook and Laboon. Both had an animal as their companions and played an instrument for them. There’s many other ways they parallel each other, but I won’t drag on this theory.
My theory for how the One Piece will be used is Luffy will play the drum and everyone will be connected through the voice of all things and they will find out the Void Century through that.
Rayleigh will hear Luffy through the voice of all things and be proud that he made it, but everyone else will be shocked, the world will be turned upside down and will be against the government and the war will begin.
Remember what Wyper said when he first heard the drums playing in the aftermath of Skypiea, “are those the sound of drums announcing the battle”. I think the drum will start the final battle and start the biggest banquet in the world.
Theory by Khalidmo1 (https://www.reddit.com/user/Khalidmo1)