I just received this reply from Paypal.
Is the below a possibility for you to setup the api call for WCV users in countries that canot use mass pay.
Let me know your thoughts.
In order to use MassPay APIs, this feature must be enabled on your account and the information I got from our customer support team tells me this is only enabled for large, account managed accounts. Unfortunately, you won’t be able to use MassPay API to send any funds to your vendors but looking at your account, I can see that your Adaptive Payments application is enabled for Implicit Payments. This is similar to MassPay API but you need to use the Pay API to make the payments. Implicit Payments allows you to send money from your balance to different receivers. Basically, your account is both the API caller and sender so there is no need for approval. Once the API call is executed, money moves from your balance to the receivers specified in your API call. You can share the example below with your developer:
https://devtools-paypal.com/guide/ap_implicit_payment (senderEmail should be same as the API caller).
Also, if this is going to take time to implement, you can send money by using the Send Money tab on your account. Please login to your account, click Send Money tab and make separate payments to receivers (one at a time, separately).