[{"_id":1,"agency":"AG1","year":"2022","month":"9","residents":[{"sequential":1,"name":"Resident 1","statusResident":"pending",},{"sequential":2,"name":"Resident 2","statusResident":"not analyzed"},{"sequential":3,"name":"Resident 3","statusResident":"not analyzed"},{"sequential":4,"name":"Resident 4","statusResident":"finished"}]},{"_id":2,"agency":"AG2","year":"2022","month":"9","residents":[{"sequential":1,"name":"Resident 10","statusResident":"pending",},{"sequential":2,"name":"Resident 20","statusResident":"not analyzed"}]}]

db.collection.aggregate([{"$unwind":"$residents"},{"$group":{"_id":{"agency":"$agency","statusResident":"$residents.statusResident"},"total":{"$sum":1}}},{"$project":{"_id":0,"agency":"$_id.agency","statusResident":"$_id.statusResident","total":1}}])