Just as confirmation for UK people who haven't tried it out yet - I set up my Switch with a South African account under a separate email address, bought Jackbox Party Pack 4 (as the language specified on the South African eShop page is English only) for 285 ZA/South African Rand (which on eshop-prices.com is about £15.39) with my NatWest debit card (so not a credit card specifically for international purchases) and was charged £15.64, so there was a 30p extra charge, but to save 20% on all future purchases I'm happy with that!
Edit: I also received an email confirmation to the email address from the NoE HQ in Frankfurt confirming the transaction in R285.00 and the correct card type.
Also, I think it's a good idea forhttps://eshop-prices.com to be added to the OP as there are some cases where a different eShop region is cheaper (Mexico, Japan etc.) - I think South Africa works for the EU region because it's considered PAL, same as Australia/New Zealand, but just something I thought was worth mentioning.
Can confirm it worked with my English VISA Debit as well. Golf Story and Stardew Valley for a combined £20.01. That's a bloody bargain if you ask me!