Assigned As A Granddaughter (1975)

Like many boys and girls whose early years included the Great Patriotic War, 16-year-old Dusya was eager to go to the front. She and her family lived not far from Sukhumi, and not a week passed without Dusya stopping by the local military registration and enlistment office. Each time the military commissar refused to grant her request, but Dusya did not give up and one day she was offered to enter an intelligence school.

Unfortunately the movie Assigned As A Granddaughter is not yet available on HBO Max.