Database

[{query_a:[{"ID":"c80ea2cb-3272-77ae-8f46-d95de600c5bf","date_a":"1"},{"ID":"c80ea2cb-3272-77ae-8f46-d95de600c5bf","date_a":"2"},{"ID":"cdbcc129-548a-9d51-895a-1538200664e6","date_a":"3"},{"ID":"cdbcc129-548a-9d51-895a-1538200664e6","date_a":"4"},{"ID":"cdbcc129-548a-9d51-895a-1538200664e6","date_a":"5"},{"ID":"a4ece1ba-42ae-e735-17b0-f619daa506f9","date_a":"6"},{"ID":"a4ece1ba-42ae-e735-17b0-f619daa506f9","date_a":"7"},{"ID":"a4ece1ba-42ae-e735-17b0-f619daa506f9","date_a":"8"},{"ID":"a4ece1ba-42ae-e735-17b0-f619daa506f9","date_a":"9"}],query_b:[{"ID":"c80ea2cb-3272-77ae-8f46-d95de600c5bf","date_b":"10"},{"ID":"cdbcc129-548a-9d51-895a-1538200664e6","date_b":"11"},{"ID":"a4ece1ba-42ae-e735-17b0-f619daa506f9","date_b":"12"}],}]

Query

db.collection.aggregate([{"$project":{"union":{"$setUnion":["$query_a","$query_b"]},"query_a":1,"query_b":1}},{"$project":{"_id":0,"data":{"$map":{"input":"$union","in":{"union":"$$this","query_a":{"$first":{"$filter":{"input":"$query_a","as":"item","cond":{"$eq":["$$item.ID","$$this"]}}}},"query_b":{"$first":{"$filter":{"input":"$query_b","as":"item","cond":{"$eq":["$$item.ID","$$this"]}}}}}}}}},{"$unwind":"$data"},{"$replaceRoot":{"newRoot":"$data"}},{"$project":{"union":1,}}])

Result