“The way we do it is they basically initiate the transaction on chain and send us the [for example] SLP. But across the markets that we operate in we actually have a fiat liquidity pool that's based in that country. We use that to settle with the merchant network,”

https://www.theblock.co/post/157808/web3-infrastructure-startup-xld-finance-raises-13m-to-build-apis-that-enable-financial-access-through-crypto