Correct, which is why the warrant was limited to computers in the United States (I don't know how they went about this in practice).
https://www.justice.gov/d9/2023-08/23mj4244_warrant_redacted...
https://www.justice.gov/d9/2023-08/23mj4244_warrant_redacted...
impossible is the wrong word here, its just unnecessary. The Feds can (and do) definitely contact domestic & international ISPs to perform near 100% accurate lookups.