Based on my understanding to get an international merchant account you dont really need to be in US or have a US company or Bank account.
Honestly you dont even need any USA company to even use US echeck and
ACH Payment Processing system to accept payments from usa based customers.
Over here in this question the major challange is the integration. Most of our Processing partners offer multicurrency payment processing but how it will integrate to apple store of google store is something that the developers can take care of
Most of the times a small HTML code can create a buy now button on the app. If this works for you then Quadrapay may help.
Happy processing.