[{"name":"#0","sales":[{"date":"2021-10-14","price":3.69,},{"date":"2021-10-15","price":2.79,}]},{"name":"#1","sales":[{"date":"2021-10-14","price":1.5,}]}]

db.collection.aggregate([{$match:{sales:{$elemMatch:{date:"2021-10-14",}}}},{$group:{_id:null,data:{$push:"$sales",}}},{$project:{data:{$filter:{input:{$reduce:{input:"$data",initialValue:[],in:{$setUnion:["$$value","$$this"],}}},cond:{$eq:["$$this.date","2021-10-14"]}}}}}])