SHENZHEN, China—From an office in Shenzhen’s sprawling electronics district, an engineering team is prototyping a bioreactor that will one day produce “cultivated meat”, discussing component sizes in a video call with scientists sitting in kitchens and bedrooms in the UK. It’s a complicated conversation about precision parts that would ordinarily need a hands-on meeting in Shenzhen, the hardware center of the world where product makers can buy and tinker with any gear they need. Hax, the firm backing the bioreactor, invests in more than 30 such hardware startups from overseas each year and would typically fly them to Shenzhen to build their products. But China’s COVID-19 border closures have paralyzed this movement of talent, throwing a spanner in the rapid cycles of product development that power Shenzhen. “We’d normally just jam with teams under one roof, rolling up our sleeves and getting involved in the electronics and chemicals, but we …