Upbit is not available in the United States, and there is no partial version or workaround. The exchange trades exclusively in Korean won, requires a Korean mobile number, a Korean ID or Alien Registration Card, and a real-name K Bank account, and its terms exclude U.S. residents. Upbit's overseas affiliates in Singapore, Indonesia and Thailand are separate companies with their own rules, and they exclude Americans too. A VPN does not change any of that, because the bank account is the gate.
Most U.S. searches for Upbit come from three places: a Korean expat or student who used it at home, a relative helping someone in Korea, or a trader who saw Upbit near the top of a volume ranking. For all three, Anytime Capital is open: a FinCEN-registered U.S. money services business that serves customers worldwide, with a branch in Atlanta, an office in Miami, a phone line at (470) 748-2530, card pricing from 4% with the spread included, and cash, ACH and same-day wire in dollars.
Bitcoin, Ethereum and the major stablecoins trade on both. What differs is the account around them: Upbit is a won balance on a Korean exchange, and Anytime Capital is a company you can call and visit, with a non-custodial wallet and an FDIC-insured cash account attached.