A trip to China with a single tool is a trip with a single point of failure. The setup that holds up has three layers.
Layer one: a way to reach home that is not a VPN. Roaming or an overseas-gateway eSIM, as above. If this works, your WhatsApp, Gmail and Maps work, and the VPN becomes a spare.
Layer two: a VPN, tested at home. Install it, sign in, and run through the settings from the sequence above while you are still in a country where everything works, so that you know where each setting lives. Write the order down on a note that is not stored in a blocked cloud app.
Layer three: a second provider. Different providers fail on different days. A backup is the cheapest insurance on this list, and many services have a refund window if you choose to cancel afterwards.
Habits that matter in China. Keep WeChat and Alipay working before arrival, because you cannot bring a Western card to a street stall. Download offline maps. Screenshot the hotel address in Chinese characters. Save your key documents offline. Tell family which app to expect you on. And if none of the internet tricks work for a day, do not spiral: a day without Google is survivable.
For the diaspora traveller, one extra: in your family chat, agree on WeChat as the emergency channel, since it works in China without any tool. We cover that angle in the pillar guide.