[{"id":"asdfasdfasdf","shipDate":"2021-04-02","packages":[{"id":"adfasdfasdfasdf","contents":[{"product":{"id":1},"quantity":10},{"product":{"id":2},"quantity":10},{"product":{"id":3},"quantity":10}]}]},{"id":"asdfasdfasdf","shipDate":"2021-04-02","packages":[{"id":"adfasdfasdfasdf","contents":[{"product":{"id":3},"quantity":10},{"product":{"id":3},"quantity":10}]}]},{"id":"asdfasdfasdf","shipDate":"2021-04-02","packages":[{"id":"adfasdfasdfasdf","contents":[{"product":{"id":1},"quantity":10},{"product":{"id":2},"quantity":10}]}]}]

db.collection.aggregate([{$match:{"shipDate":"2021-04-02","packages.contents.product.id":1}},{$unwind:"$packages"},{$project:{contents:{$filter:{input:"$packages.contents",as:"contents",cond:{"$eq":["$$contents.product.id",1]}}}}},{$unwind:"$contents"},{$group:{"_id":null,"total":{"$sum":"$contents.quantity"}}}])