At the moment, Universal App can only support Stripe as a payment method, so using Stripe is required when you want to offer issue purchases or subscriptions with your Universal App.
If you don't have a Stripe account yet, you can check out their guide here on getting started.
As we currently only use Stripe, we also only support currencies that are supported by Stripe. At the moment, Stripe supports processing payments in 135+ currencies. Stripe also allows you to charge your readers using their native currency, while still receiving the funds in your own currency.
You can check out the list of Stripe's supported currencies here.