Published
CGFNS exam is not a mandatory exam for licensure in the US. The only two exams are NCLEX-RN and the series of English exams, if you are not exempt from them.
The CGFNS exam is waived for Michigan if you are a Canadian nurse, or have worked for at least five years in the US as an RN. It is currently the only state where you cannot get licensed in another state, then endorse to there.
Illinois recently abandoned its requirement for the CGFNS exam, and now only requires the CES.
Most states are now just requiring the Credentials Evaluation Service (CES) done by CGFNS. This is different than the exam.
Immigration only requires that one exam be done, CGFNS or NCLEX. You will ultimately be required to sit for the NCLEX exam, so if you can afford to take that one, then that is the way to go.
Hope that this clears up any rumors that are flying around the world at the moment.