For years now, One Piece fans have been trying to decipher the identity of the next member of the Straw Hat Pirates. While this happens during every arc whenever an important or interesting character is introduced, the hype over the next addition to the team grew exponentially in 2020. At the beginning of the series, Luffy said that he was going to recruit 10 members to his crew, but around three years ago in the official One Piece magazine, it was confirmed that these 10 wouldn't include himself, meaning there is still one Straw Hat left.
Source:https://www.cbr.com/one-piece-vivi-last-straw-hat-early-reveal/