TypeError: Object of type 'DataFrame' is not JSON serializable

Your df is still a data frame because you haven't assigned it as json.

   df = df.to_json()

This should work. Let me know if not.

df = pd.read_csv(data)
return_data = {
    "status": 1,
    "message": "Raw Data List with pagination",
    "data": {
        "is_header": is_header,
        "head": **json.loads(df.head().to_json())**
    }
}