Could a student brush up and take the AP test this year? Sure they could.
How well the material aligns with the AP test would depend on what was covered during the school year.
I’d have the student get a review book out from the library and see if there was enough of an overlap to make it realistic.
The only hurdle that a student may face is finding a seat to take the test because some high schools limit who can sit for AP tests. I would hope that in this case, the school would allow it.
That all said, if the class is on a student’s transcript, that should be enough for a college. The common app has a place to put covid disruptions and a student could write that the AP wasn’t offered that year because of Covid.