It has been ruled by SCOTUS that the Constitution specifically does not apply at border entry to non-citizens:

https://en.wikipedia.org/wiki/United_States_ex_rel._Knauff_v._Shaughnessy

the Constitution does not grant aliens any protections when trying to enter the United States.

https://constitution.congress.gov/browse/essay/artI-S8-C18-8-7-3/ALDE_00001263/[‘article’, ‘14’]

an alien “on the threshold of initial entry stands on a different footing” because he or she is theoretically outside the United States and typically beyond the veil of constitutional protection.

https://supreme.justia.com/cases/federal/us/345/206/

Although a lawfully resident alien may not captiously be deprived of his constitutional rights [to due process], the alien in this case is an entrant alien or “assimilated to that status” for constitutional purposes.

The Attorney General therefore may exclude this alien without a hearing, as authorized by the emergency regulations promulgated pursuant to the Passport Act, and need not disclose the evidence upon which that determination rests.