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',%20'14']
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.
duckduckgo, icon.horse and favicongrabber.com also have their own APIs for this
I bet there is a way this could be abused in order to proxy/tunnel arbitrary requests via google IPs. Even if it's slow and must be done through e.g. PNG image data and dynamic subdomains or something, it would still be possible.