Iirc a judge stopped the systematic requirement to inspect, but if you're not a citizen and refuse they can put you in the deportation gulag for a couple weeks and I guess not look at the phone. Not legal advice.

I wonder what usually travels if one travels with a burner phone (a phone obviously barely previously used) to the US, or in other places where one would not want to risk their phone getting confiscated. Is there any experience on that? Should one try to build some plausible deniability on that (eg use lightly a phone for a while for it to at least appear used)?