Tech giants have become tech dwarfs in China in the wake of COVID and a government crackdown on cutting-edge tech. Crypto conferences used to be quite the scene in Shanghai: fancy venues in five-star hotels, rooftop bars overlooking Huangpu River at The Bund, where chandeliers sparkled above well-dressed, champagne-sipping attendees, chatting the night away before heading out to clubs where more champagne gets poured. That scene is no more, now that China’s “zero Covid” policy has turned the buzzing city into a ghost town. Some residents have reported being cooped up in their homes for three months, not once stepping...