eSIM is currently being deployed by 3 major carriers in Vietnam. However, currently only iPhone XS / XR is a product line of genuine phones that are supported eSIM. If you want to use on some other models like Pixel 3, Pixel 2, is it okay?
The answer is of course. And I successfully tried attaching the eSIM to the Pixel 3 purchased from the US. For Pixel 2, eSIM only supports Google Fi service not available in Vietnam.
In this article, I registered a new eSIM from Vinaphone. They provide a QR code to use scanning from the phone. The problem with the Pixel 3, however, is that when the device is activated and using a SIM card, attaching the eSIM is not possible. Perhaps Google knows that this Pixel 3 is being used in a market that is not yet supported with official eSIM?
So I found out that we can attach eSIM to the Pixel 3 when the device is not activated via the internet (Wi-Fi) by logging into a Google account. Thus, when logging in outside the US market, Pixel 3's software understands that users are using other devices in the market, not supporting eSIM, so they hide and not use.
I have successfully tried to attach Vinaphone's eSIM to Pixel 3. There are two Viettel and Mobifone networks that I have not tried, so I don't know how to calculate compatibility. Basically, if a QR code of eSIM has been installed on another device, it can be a one-time use, if you want to switch to another machine, we must re-apply QR code to increase security.