Database
[{"_id":"62b9c1d74321afff4cb4e652","created":"2022-06-27T14:42:31.726Z","pin":"2022-06-27T14:42:31.703Z","pin_order":1},{"_id":"62b55d6ee0e1fa12861f8cb8","created":"2022-06-24T06:45:02.126Z","pin":null,"pin_order":1},{"_id":"629a212eda64722e286d29f6","created":"2022-06-03T14:56:46.980Z","pin":null,"pin_order":1}]
Query
db.collection.aggregate([{$set:{"sortField":{$cond:{if:{$ne:["$pin",null]},then:"$pin_order",else:9999999}}}},{$sort:{sortField:1,created:1}},{$unset:"sortField"}])