How mobile-friendly is S7 Airlines?

S7 Airlines provides an iOS app that is compatible with iPhone, iPod, and iPad.

For S7 Airlines S7 Priority members, you'll be able to manage your account from the app, though using their website will no doubt provide more functionality

The Android apps from S7 Airlines work with all Android phones and tablets from various manufacturers (Samsung, LG, Google, etc.), and Android Wear watches might also be compatible. As you might expect, the Android app from S7 Airlines has the same familiar functions as the iOS app.

Also take a look at S7 Airlines's website by clicking here — you should be able to do what you need there.