I don't know it deeply but what NP does is lets me pay in sats and converts to local currency for the merchant. This is the only way Vietnamese businesses are interested to let me pay with lightning. It's illegal for them to accept payment in currency that isn't dong so this is a good little work around. No KYC to set up but I think probably some kind of kyc process to link to Vietnamese bank account. My app store is Aussie so I haven't been able to test it out yet. I'm tempted to buy another phone and set up a Vietnamese app store just to try for myself 😆