Most esims work fine, the data will tunnel to your esim provider without issue. you can have a VPN setup for wifi, but VPNs can stop working randomly so be prepared to change endpoints ot have a backup pre installed.
Cash is effectively dead, your going to need alipay or WeChat setup to be able to pay for anything, including like tiny vendors in the middle of no where. Don't expect anybody to take cash, or make change, if they do take it it's because they are being nice.
Setup your WeChat / Ali / maps / taxi before you go there. Google maps will be wonky because of the map distortion they are required to have.
Take two phones, yes, when you install some chinese only app, having a second phone to do Google lens translate will be a life saver.
Predownload your translation apps and data packs. And test! Put your phone into airplane mode and make sure it does the needful without internet access.