Reminder to fellow travelers: disable biometric-based device access when crossing the US border. It may not prevent your stuff from being cloned, but it may matter down the road as more case law is established.
The idea of handing my phone to an agent of the government without physical compulsion is abhorrent to me, and is something I hope to never engage in. For this reason, mobile boarding passes are a non-starter. (see also: wireless keyboards)