I turn off biometrics and power down. They can ask for the unlock pin, I can decline until they produce a warrant and I can request an lawyer. My risk profile is sufficiently accommodated.
I can see someone with a different risk profile, say, an online presence showing vocal criticism against Trump and goons, and/or not white and/or not a native born US citizen and/or has a travel history to muslim-majority countries might want to take further measures.
I've just skimmed headlines and seen a short or two on the guy who gave LEOs the distress pin. I'm not sure why he didn't decline to give them his pin until they produced a warrant, but I think giving a destruction pin was not the brightest idea. But also, fuck the cops and double fuck border cops playing these racist, fascist games with people's lives.