Shanks is currently the most capable person who could find the One Piece. He’s a Yonko and a former member of the Roger Pirates and was possibly present when the crew found Raftel.
Of all the known living characters who were formerly members of the Roger Pirates, Shanks, Buggy, Rayleigh, Crocus, Nekomamushi, Inuarashi, none of them have ever shown interest in finding the One Piece even though it would be relatively easier for these individuals to find it.
Though Buggy has stated that he would want to be the Pirate King, this does not definitely mean that he is interested in finding the One Piece. Luffy states that the Pirate King is the man with the most freedom in the world, and knowing that Buggy has a love for finding and owning various treasures it’s quite interesting that he would not even attempt to find the One Piece, which is the most sought-out treasure in the world. Buggy may have his own definition of what a Pirate King is , as Luffy does. It would make more sense if Buggy had spent years trying to reach Raftel on his own but eventually gave up, but Buggy has shown no intention of even seeking the One Piece.
If Buggy gave up on finding the One Piece because he was too weak then definitely Shanks would have been able to find it, being a Yonko and having various territories in the New World.
Silvers Rayleigh would not really need to find the One Piece or be involved with it anymore as he is now retired. Rayleigh also has knowledge about the Void Century which could throw the world into chaos if it made public. However, Rayleigh’s disinterest in doing this shows that he really isn’t interested in being involved with this “new era”.
This leads to my theory that while disbanding the Roger Pirates, Gol D. Roger himself could have asked his members not to seek out the One Piece as he wanted the “one” who was destined to find the One Piece to find it themselves. Yes, Roger did say anyone who wanted the One Piece could go find it, but he could simply have been speaking with his crew understanding that he was excluding members of the Roger Pirates.
This “one” is stated by Whitebeard while talking to Teach about who would find the One Piece. Rayleigh also sees more of Roger in Luffy when he refuses to learn about the One Piece’s location and secrets. This could be because he had met the person who Roger was talking about in Luffy. However, the fact that Rayleigh was willing to tell the Strawhats the location of the One Piece, despite not knowing that Luffy would refuse to listen possibly means that simply knowing where Raftel is does not guarantee that a person or crew can get there.
Despite this, it is still likely that Shanks and Buggy would have been able to reach Raftel and find the One Piece if they wanted to and therefore haven’t found it because they don’t want to find it.
Roger “banning” his crew from seeking the One Piece would mean that he truly wanted the next “Pirate King” to be the one who deserves to find the One Piece and not just the person who discovers its location.
Gol D. Roger searched for Raftel in order to successfully conquer the Grand Line and so it would make sense if he wanted the person who would find his treasure to go through the same journey and search he did in order to become the Pirate King.
*Theory by TheMeans
