Anybody crossing the border. The justification is that the government's constitutional right to control imports overrides the 4th amendment right to privacy.

>“The border-search exception is grounded in the recognized right of the sovereign to control, subject to substantive limitations imposed by the Constitution, who and what may enter the country.” Id. at 620. Because “[t]he Government’s interest in preventing the entry of unwanted persons and effects is at its zenith at the international border,” United States v. Flores-Montano, 541 U.S. 149, 152 (2004), “searches made at the border, pursuant to the long-standing right of the sovereign to protect itself by stopping and examining persons and property crossing into this country, are reasonable simply by virtue of the fact that they occur at the border,” Ramsey, 431 U.S. at 616.

https://ww3.ca2.uscourts.gov/decisions/OPN/24-960_complete_o...

Near the top of the article:

“Today’s decision leaves Americans’ most sensitive information open to search at the border without any suspicion at all,”

I think this is just an extension of a general we, as government officials protecting American freedoms, can do what we want and will justify it later if we have to policy.

It should probably be noted that this specific case led to a conviction of an actual crime (Bank fraud and money laundering).

It probably depends how pissed off you made the officer at the border if he just wants to thumb through some recent text messages and photos to see if you're doing Crimes or if they're gonna go take it to the Cellebrite UFED in the backroom and dump it out.