Firework is gaining acclaim for eye-popping tech innovations such as video commerce in which lifelike AI avatars talk shoppers through a sale. But for Vincent Yang, Firework’s co-founder and CEO, an underappreciated challenge of such futuristic shopping tech is building it on material—the website—that is still stuck in the 20th century. “I feel like it is the biggest hidden secret that nobody is really tackling,” Yang said.