More than a bit obsessed with Captain America/Peggy Carter pairing the past week. Reading tons of fanfic on the subject.
In my AU head canon Agent Carter doesn’t age because when she and Cap kiss in “Captain America,The First Avenger” she gets some of the super soldier serum from his DNA. The nursing home in is a ruse and she’s under tons of makeup. At some point, when needed, she will join Cap in kicking butt.