Hi yes my son was born in Thailand with a Thai Mother and i am from the U.K
Probably the best advice is to see how it goes he has already opened a Ebay account and managed to get registered with Payoneer after a few attempts.
He registered on Shopify or wix not sure which one but has problems with getting a thai credit card registered.
I was told if you sell lots of items to other countries you will need to pay tax also but maybe that's only if the bank is in the UK
He has managed to open a UK account when we were there at the start of this year which i was surprised with but probably not a good idea to have money going into a UK bank and then sent to his Kasikorn bank ?