Dany Nomads Tagthai app for QR code payment for tourists

In Thailand you need TagThai to pay by QR codes. I believe you can connect Wise cards (physical or virtual) to Tagthai.

As to your question about own currency versus local, you should ALWAYS pay in the local currency if asked. Banks make millions out of people's silly nationalism, choosing their own currency. If you don't believe it, just try it some time. Make a mental note of the conversion offered but decline and pay in local. Compare the actual amount you were charged after conversion and you will see what a rip off it is to choose your own currency 😅