Can a foreigner make a purchase in App Store China? I want to make an IAP on my Chinese App Store account. I live in China so all the other information including mobile phone and valid address is not a problem. 

So I can create an account and download apps. But when I try to make a purchase, I hit the wall as there seems no way to finish the payment.

Both WeChat and Alipay don’t accept the foreigners account. The credit card is acceptable but only cards issued in China are acceptable, which I can’t have. Also the bank transfer is not acceptable as it requires to type in a valid Chinese citizen number, which I cannot fill in using my passport number.

So I wonder there is a way to make a purchase in Chinese App Store as a foreigner.
It looks like that Chinese App Store accepts China UnionPay cards. If you have any Chinese bank debit card, you can pay for in app purchases easily.

As per Apple Support: 

China

If you're purchasing iCloud storage, an Apple Music subscription, or content from the App Store in China, you can use:

    Alipay
    China UnionPay
    Online banking2
    WeChat Pay
    Gift cards (including App Store Top-Up cards)

UnionPay and Chinese bank cards    
When you add UnionPay as a payment method, you must provide the mobile phone number your card's issuing bank has on file for you.

Some cards do not have mobile numbers associated with them. If this is the case with your card, contact your bank to update or replace it.

App Store Top-Up cards    
You can also redeem App Store Top-Up cards for store credit in China.