Can a State impose more restrictive screening for certain States that

[karynnj]

5. I believe that they were in effect for much of a year (split between 2020/2021)

They did not say that people , could not come, but from most states, but a 14 day quarantine even for returning Vermonters, was required or the results of a negative test after arriving. This was first waived if fully vaccinated.

Friends who recently went to Hawaii needed tests before they could get on the plane to Hawaii - even though fully vaccinated. I think that just ended.

As to if these regulations were legal, I read nothing on them being successfully challenged.