items = [
{'id': '111111111', 'username': 'milk'},
{'id': '222222222', 'username': 'yogurt'},
{'id': '333333333', 'username': 'cat'}
]
items_id = [item.get('id') for item in items]
items_username = [item.get('username') for item in items]
print(items_id)
# ['111111111', '222222222', '333333333']
print(items_username)
# ['milk', 'yogurt', 'cat']