I know just the papers they were going to file for because my friend, who married a Polish woman, in Poland around 1979 and after a few years living first in England to finish his doctorate at Oxford, then in Belgium, applied to bring his wife to the U.S. It took 18 months and not so few hundreds of dollars, even then, to make all legal.
After that, it took her 7 years to apply for her citizenship, plus more money and citizenship classes, so she could pass her test!
It is not easy or cheap to go through the process legally. Nor should it be, but sometimes the “bureaucracy” is, as one might expect of FedGov, pretty overdone.