using sqlalchemy, transfer one million table records in 10,000 increments with select fields from mysql to postgresql without pandas

from sqlalchemy import create_engine

postgres_str = 'postgresql://localhost/postgres'
mysql_str = 'mysql+pymysql://localhost/mysql'
  
mysql_engine = create_engine(mysql_str)
postgres_engine = create_engine(postgres_str)

sql = 'select * from tablename'

def insert_sql_table_to_postgres(column_names, sql, mysql_engine, postgres_engine):
  """
  column_names: list of the column names from the mysql table
  sql: string of sql to select from the mysql table
  mysql_engine: sqlalchemy engine for mysql
  postgres_engine: sqlalchemy engine for postgres
  """
  
    df = pd.read_sql(sql, mysql_engine)
    df = df.head(1000000)
    
    conn = postgres_engine.raw_connection()
    cursor = conn.cursor()
    
    chunks = list(pd.read_sql(sql, mysql