I have a problem. I have a nested JSON file:

json_data = '''
{
    "appVersion": "",
    "device": {
        "model": ""
    },
    "bef": {
        "catalog": ""
    },
    "data": [
        {
            "timestamp": "",
            "label": "",
            "category": ""
        }
    ]
}

I would like to extract all data and if it is nested I would like it to be separated with a _.
I have tried to normalise the nested JSON file. I use json_normalise for this.
Unfortunately, the desired output is not what I want and need.
Furthermore, I want that there can be any possible number of nested values, so I tried to solve it with a loop.

How can I produce the desired output?

import pandas as pd
import json

json_data = '''
{
    "appVersion": "0.0.3",
    "device": {
        "model": "Lenovo"
    },
    "bef": {
        "catalog": "Manual"
    },
    "data": [
        {
            "timestamp": "2024-04-24 12:08:02.415077",
            "label": "zuf",
            "category": "50"
        }
    ]
}
'''
parsed_json = json.loads(json_data)

def extract_metadata(json_data):
    metadata = {}
    for key, value in json_data.items():
        if isinstance(value, dict):
            for k, v in value.items():
                metadata[f'{key}_{k}'] = v
        else:
            metadata[key] = value
    return metadata

meta_data = extract_metadata(parsed_json)
df_main = pd.json_normalize(parsed_json['data'], sep='_')
df_meta = pd.DataFrame([meta_data])
df = pd.concat([df_main, df_meta], axis=1)


print(df)

What I got

                    timestamp label category appVersion device_model  
0  2024-04-24 12:08:02.415077   zuf       50      0.0.3       Lenovo   

  bef_catalog                                               data  
0     Manual  [{'timestamp': '2024-04-24 12:08:02.415077', '...  

What I want

appVersion  device_model    bef_catalog data_timestamp          data_label  data_category
0.0.3       Lenovo          Manual      2024-04-24 12:08:02.415 zuf         50