const schedule = {
  date: '0305',
  meeting1: {
    id: '00001',
    start: '10:30'
  },
  meeting2: {
    id: '00002',
    start: '12:30'
  }
};

function getNestedObjValuesByQueue(obj){
  let queue = [obj]
  let values = []
  while (queue.length > 0){
    let current = queue.shift();
    for (let val of Object.values(current)){
      if(typeof val === "object") queue.push(val);
      else values.push(val);
    }
  }
  console.log(values)
}

getNestedObjValuesByQueue(schedule)
 Run code snippet