@Nessa1 , sorry, the preceding was late in evening, and I realized sometime aftter that you have apparently never purchased the iOS Scrivener before.
Here is Apple’s statement about what they would accept: https://www.apple.com/shop/help/payments
I would think to use PayPal, of what you’ve mentioned. Prepaid cards are tricky at best for online acceptance; it seems MasterCard ones are much worse (more restricted) in this sense than Visa, but I still wouldn’t tie money up in one to find out.
It seems that to make any method work, you have to get Apple to allow you not just to have a purchase, but to be allowed to download in whatyever mystery country you are not mentioning. The countrry itself may also have opinions about that, it seems you may recognize.
I started to find and give you an earlier link I had, which felt coquettishly that Apple ‘may’ check your iPad Location as well as apparent address from a VPN. This article suggests, in an ambling way, that you ‘may’ need some form of GPS spoofing. This is danterous territory at best, because you don’t know what else an app offering this may do - or be connected to, considering local legal matters again.
Instead, though, I’ve found a better article (all of these will try to sell you from their list of VPNs). This onw has detaied steps, including simply turning off the iPad Location Services, to avoid the GPS problem. I would read it all, carefully, until you have it well in mind what you need to do, and know where to find the adjustments. Also have thought through how to reverse the process once you are done!!
Your first step would be to sign up for a good iPad VPN - NordVPN seems recommended by these articles, has been felt reputable by journals at least for some years, and as I just looked, has a 30 day free trial.
Once you had that working and tested as showing you in the US (using whatismyipaddress.com for example, which gives the location as well), then you would do the steps to turn off GPS Location services, and alter your AppleID address.
At this point you can see if you can get PayPal to work for you, which will involve your Stateside credit card or bank account.
Then you see if you can get the Apple Store to let you in, with US presence, and then to accept your PayPal account as payment source.
If all that is successful, you ought to be able to purchasse Scrivener iOS, and one would think it would immediately download in the usual way as well.
If for some reason of their cleverness you are able to purchace, but can’t seem to download, then the tip I put above seems it ought to work for you. It’s hard to say, and this would in that case be after you unwound so that your AppleId was again where you are, and using it without VPN and likely with locaiton services back on so that you look properly in place.
I think you’ll properly undrestand from this account that this is nothing of a solution which is sure to work. But given you stay on the side of proper behavior, it’s the kind of adjustment we sometimes do have to make, living out in the world from where we originated.
Staying within that behavior which will be judged proper is essential, I have always found in many circumstances. I caution you to do so. It would be very nice to have Scrivener on your iPad, but not worth risks.
It’s worth considering that having Scrivener on a Windows machine (or Mac) is much to be recommended along with the iPad, as it has much more functionality, howver nice and capable the iOS version actually is. And you can ask how much it would cost to get your device repaired, or to purchase perhaps a used model just to run this, as Scrivener’s needs are not high for the computing hardware.
Best fortune, then, and hope to have let you see enough to consider your own safe and appropriate balances.