db={"processes":[{_id:ObjectId("63d96b68e7b92dceb334f4cb"),status:"active",history:[{type:"created",userID:"61e77cdedde2dbe1cbf8a250",date:"Tue Jan 31 2023 17:31:32 GMT+0000 (Coordinated Universal Time)"},{type:"updated",userID:"d6xMtHTIX3QO0FifUPgoJLOLz872",date:"Tue Jan 31 2023 18:31:32 GMT+0000 (Coordinated Universal Time)"},{type:"updated",userID:"61e77cdedde2dbe1cbf8a250",date:"Tue Jan 31 2023 19:31:32 GMT+0000 (Coordinated Universal Time)"},]}],"users":[{_id:"d6xMtHTIX3QO0FifUPgoJLOLz872",uid:"werwevmA5gZ2Ky2MUuSAj6TJiZz1",email:"something@something.com",firstname:"Bobby",lastname:"Tables",},{_id:"61e77cdedde2dbe1cbf8a250",uid:"uid1",email:"something2@something.com",firstname:"Jenny",lastname:"Tables",}]}

db.processes.aggregate([{$unwind:"$history"},{"$lookup":{from:"users",localField:"history.userID",foreignField:"_id",as:"userLookup"}},{$unwind:"$userLookup"},{$project:{status:1,history:{type:"$history.type",userName:{"$concat":["$userLookup.firstname"," ","$userLookup.lastname"]},date:"$history.date"}}},{$group:{_id:"$_id",status:{$first:"$status"},history:{$push:"$history"}}},{"$merge":{into:"process",on:"_id",whenMatched:"merge"}}])