Question: Nintendo Switch Console – What regions/countries will the eShop credit code work for?
The e-shop Credit is for North America region ONLY. You can have one Switch account on the system for each region though, so downloading demos, from say, Japan’s e-shop is also possible. (with a 2nd email and I used a translation guide.) So you can buy credit from other regions, and use the credit with any account of that region attached.