[{"id":"myid","field":{"total":1,"subfield":[{"somefield":"1000","time":ISODate("2020-08-06T03:03:57.977Z"),"val":[{"x":"someval","a":"val1","b":"val2"}]},{"somefield":"2000","time":ISODate("2020-05-07T22:43:27.977Z"),"val":[{"x":"someval2","a":"val1","b":"val2"}]}]}},{"id":"myid2","field":{"total":1,"subfield":[{"somefield":"1001","time":ISODate("2020-07-31T04:45:50.184Z"),"val":[{"x":"someval2","a":"val1","b":"val2"},{"x":"someval2","a":"val1","b":"val2"}]}]}}]

db.collection.aggregate([{"$project":{"obj1":{"$filter":{"input":"$field.subfield","as":"el","cond":{"$and":[{"$gt":["$$el.time",new Date("2020-04-29")]}]}}},id:1,}},{$match:{$or:[{"obj1.val.a":{"$eq":"val1"}},{"obj1.val.b":{"$eq":"val1"}}]}},{$project:{id:1,_id:0}}])