What do u think of binance app on mobile then ?
Mostly the same.
If you are using google authenticator AND the binance application on the same device, you are not secured by a 2-factor-authentication.
2FA implies two devices.
Mobile apps or not, due to convenience some of us can actually not resist accessing the web interface of these exchanges directly from our phones instead from a desktop/laptop. This basically defeats the whole purpose of two devices.
I guess risking only a small amount on the exchange, like you said, is the only reasonable option.