From what I've heard about TSA I'd already hesitate bringing my main phone to the US at all, let alone one that's connected with my ID. And what if the phone dies during a trip? Now you've got the 2FA problem but with borders instead of just a Gmail login. Fantastic.
I don't think saving a few grams of paper is worth all that.
I don't think saving a few grams of paper is worth all that.