Chinese tech companies treading water amid a weakening domestic economy are increasingly looking across the Pacific for support.Whether American consumers and policymakers will provide them a lifeboat remains to be seen.Buoyed by the success of ByteDance-owned TikTok and fast-fashion e-commerce star Shein, several of the republic’s tech leaders have recently announced plans to broaden their business in the States, a market that Chinese firms have largely struggled to penetrate. Bloomberg confirmed Monday that Pinduoduo , a Chinese giant rooted in the odd pairing of agriculture and social e-commerce, is preparing to expand into North America as it seeks “new growth…