I can confirm that you are completely right about Vietnam mobile networks. I could only reliably work after getting a real viettel sim. Even viettel branded stores sell some bootleg sim to tourists that work terribly.

The problem with eSIM is that usually there is no way to judge the quality until you buy one, so people sort by price and choose the cheapest. If your solution offers the best network in the country then I’m interested, because even at x2 or x3 price it doesn’t matter much compared to the other expenses when traveling.

Not sure how you can convince customers outside the hn bubble.