db={from:[{foo:[{bar:[{_id:ObjectId("63f508eedd2962118c37ea36")}]}]}],collection:[{_id:ObjectId("63f508eedd2962118c37ea36"),field1:"helloworld"}]}

db.from.aggregate([{$lookup:{from:"collection",localField:"foo.bar._id",foreignField:"_id",as:"bars",},},{$set:{foo:{$map:{input:"$foo",as:"foo",in:{$mergeObjects:["$$foo",{bar:{$map:{input:"$$foo.bar",as:"bar",in:{$mergeObjects:["$$bar",{$first:{$filter:{input:"$bars",cond:{$eq:["$$bar._id","$$this._id"]}}}}]}}}}]}}}}},{$unset:"bars"}])