Нормализация вложенного (иерархического) Json в Python

Вы можете сделать это, определив пользовательскую функцию выравнивания и функцию обработки:

import pandas as pd

def flatten_json(y):
    out = []

    def flatten(x, name=''):
        if isinstance(x, dict):
            for a in x:
                flatten(x[a], name + a + '_')
        elif isinstance(x, list):
            i = 0
            for a in x:
                flatten(a, name + str(i) + '_')
                i += 1
        else:
            out.append((name[:-1], x))

    flatten(y)
    return dict(out)


import json

data = {
  "prod": "Food",
  "id": "F1",
  "item": [
    {
      "prod": "desserts",
      "id": "d1",
      "item": [
        {
          "prod": "chocolates",
          "id": "c1",
          "item": [
            {
              "itemdesc": "Kitkat",
              "id": "kit"
            },
            {
              "itemdesc": "Dairymilk",
              "id": "Dai"
            }
          ]
        },
        {
          "prod": "icecream",
          "id": "id2",
          "item": [
            {
              "itemdesc": "amul",
              "id": "ice"
            }
          ]
        }
      ]
    }
  ]
}

def process_json(data, parent_prod=None, parent_id=None):
    rows = []

    current_prod = data.get('prod', 'NA')
    current_id = data.get('id', 'NA')

    rows.append({
        'prod': parent_prod if parent_prod else current_prod,
        'id': current_id,
        'item': json.dumps(data.get('item', [])) if 'item' in data else data.get('itemdesc', 'NA')
    })

    if 'item' in data:
        for item in data['item']:
            rows.extend(process_json(item, current_prod, current_id))

    return rows

flattened_data = process_json(data)

df = pd.DataFrame(flattened_data)

print(df)

что даст тебе

         prod   id                                               item
0        Food   F1  [{"prod": "desserts", "id": "d1", "item": [{"p...
1        Food   d1  [{"prod": "chocolates", "id": "c1", "item": [{...
2    desserts   c1  [{"itemdesc": "Kitkat", "id": "kit"}, {"itemde...
3  chocolates  kit                                             Kitkat
4  chocolates  Dai                                          Dairymilk
5    desserts  id2                [{"itemdesc": "amul", "id": "ice"}]
6    icecream  ice                                               amul