Why would you need to reload touch n go when you are in China? You plan to use touch n go to pay for stuff when in China?

Technically can connect to hotel WiFi and just reload touch n go...

actually be it roaming or using china sim, both should be fine.

but depending on the top up method, if OTP is required, then you should not be using the china sim.

Just back from ChengDu & ChongQing, 40 degree everyday..  Mala hotpot everyday... still survive 

Mobile payment

Alipay - cover 99% of scenario, from e-hailing, restaurant reservation (via DianPin), payment, renting power bank, restaurant ordering
I only encounter where a least famous ancient park in outskirt of ChengDu receive only WeChat pay
Even the roadside stall selling fruits can paid via Alipay

How to use alipay - link Wise

WeChat pay cant be used in MSIA anymore, but you can change the wallet region to Mainland China, go to Pay and service > 3 dots upper right > change region
* Few restaurant ordering system is slow in alipay but smooth with WeChat

How to use alipay - link Wise

Internet
I bought local telco 15 days 30GB in airport (120 yuan should be), you can use roaming too, but my experience is quite some of the places dont have good coverage and some application or restaurant ordering app cant be loaded on roaming.
Me myself brought a old mobile and do hotspot with the china sim, while own phone activate roaming

Another benefit of owning a local number would be --- you able to register local app (including restaurant / cafe app) and you get bunch of new user voucher! Trust me! Get one number 
Why not VPN?
I have both ExpressVPN and NordVPN, both not working in iOS, but working with Android.
Even connected but still the speed is not promising
So end up i use the old android phone as hotspot for sharing the China Sim network