I watched a movie last night that took place in a cloistered convent, where the nuns took great pains to avoid ever having contact with anyone outside of their abbey, including having their food and supplies delivered to a dropoff point from which a nun would later pick them up when the delivery guy was far away.
In such a convent, how would a nun give her confessions? Like, does a priest come by from time to time?
Yes, a priest came regularly, for mass and confession.
Up until the Vatican II council, there were sisters “de choeur” who stayed apart the world and “converses” who were authorized to go in the world.
The priest was often the only man the 'Choeur" sisters could see and, well… there have been some shenanigans…
I grew up in a small and rather Catholic town in Bavaria that is home to a convent (not a cloistered one, though). Pastorial duties for that convent were shared between the local parishioner and retired priests from the surrounding towns and villages; Catholic priests are usually full-time employees, but they retain their ordination status and associated sacramental powers even after retirement, and are expected to help out occasionally.
Recruitment of priests is a big problem for the Catholic church, mandatory celibacy deters many interested candidates. Even a lot of parish positions are difficult to fill and need to be covered with some sort of sharing arrangement for a while.