How mobile-friendly is Vietnam Airlines?

There is an iOS app from Vietnam Airlines which will work on your iPhone, iPod, or iPad.

For Vietnam Airlines Lotusmiles Program members, you'll be able to manage your account from the app, though using their website will no doubt provide more functionality

Vietnam Airlines has an Android app that works with most Android tablets, phones, and some Android Wear devices. As is often the case, the Android app offers the same functionality as the iOS app.

Also take a look at Vietnam Airlines's website by clicking here — you should be able to do what you need there.