I registered Alipay with malaysia number. Use Apps within Alipay like for Trains (scan payment) and also Didi without having china number. My roaming was Digi.
So basically you can use without a need for China number, the negative is if driver see your MY number he wont call you and will also be annoyed if cannot find you.
I did not face any real problems, just make sure you have correct pickup point.

Having an Esim (data only) doesn't make any difference with MY Sim roaming except cost. It basically gives you internet data access. nothing to do with Call function.
I did have other family member using Esim, and Alipay works the same.

Note. China telco number/esim you cannot access most social media including whatapps/insta/tictok/google suite. MY roaming sim you can.

Yeah i saw that roaming is expensive hence opted for esim (data only) but apps such as didi always asked to register phone number so not too sure if the didi app will be tied to the number that i register..... or it is just a registration process? So basically as long as we have internet connection both  alipay and didi can work?

which SIM is best to use? still need VPN to access google etc?