Google 2 Step Authentication is Not Scary
BUT! 2 Step Authentication WILL NOT WORK if you are in flight mode. It requires that you are able to check in with google's authentication servers.
If you plan to use flight mode with the Unlock App YOU MUST ENABLE PIN AUTHENTICATION.
Enable it even if you don't plan on needing it!
If you have enabled 2 Step Authentication in your google account then you will find nothing changes after your initial re-login on your phone or tablet once you verify apps which require it.
The NFC Ring Unlock App will however require an app specific password.
Creating an app specific password will require logging in to your google account via a trusted computer and navigating to Account Settings|Security|App Passwords.
Enter a name for the password you are generating so that you will know what you are revoking at a later date, click generate password.
The next screen is the ONLY time that you will see this password. Write it down if you will need to use it more than once.
Revoke it as necessary after use.
If you are 'stuck' in flight mode and have not set the 'use without lock screen' flag, I have found that waking the device then holding the wake button again will bring up the power off menu which should allow you to switch back out of flight mode. You will then be able to use the app specific password.