How to move Google Authenticator to a hardware device?

Have a look at the reflashed tokens Protectimus Slim mini. These tokens support NFC technology and with the help of a special app you can change their secret keys. This app also reveals all characteristics of the token and gives an opportunity to adjust the OTP-passwords’ lifetime.

Google Authenticator is an implementation of the OATH TOTP and HOTP standards. So what you're looking for is a 'programmable OATH hardware token'.

The PROTECTIMUS SLIM mini is one option. It's a stand-alone battery powered token that you program using an Android device over NFC.

The YubiKey is another option. It has no display or internal clock, so it must be used with a computer and the Yubico Authenticator app to set up new tokens and to read the one-time passwords. The YubiKey NEO also works with Android devices over NFC. The secrets never leave the YubiKey. The advantage of the YubiKey over the PROTECTIMUS SLIM mini is that the YubiKey can serve as multiple tokens, where as the PROTECTIMUS is just one.