Is there any way to call an external function from priority_weight parameter in task to get the value from a config file.

My DAG looks somewhat like this:

    dag=DAG(
        'Priority',
        default_args=args,
        schedule_interval=None,
        tags=["test_priority"],
        catchup=False,
    )

    FILE_TRANSFER_TO_VM=BashOperator(
        task_id='{0}'.format(var_file_transfer_to_vm),
        bash_command='gsutil -m cp gs://folders/files gs://otherfolder/),
        priority_weight=5,
        weight_rule='absolute',
        dag=dag
    )



What I am looking for is:

file: config.cfg
    x.a=11
    y.b=22
    z.c=33

file: get_priority.py

    file_path = 'config.cfg'
    def fetch_value_from_cfg(context):
        key = context['task_instance'][0] ##To get dag_id.task_id from context lets say 'y.b'
        print(key_prefix)
        with open(file_path, 'r', encoding='utf-8') as file:
            for line in file:
                if line.startswith(key_prefix):
                    return line.split('=')[1].strip()
        return None



Dag file: Priority.py


    import get_priority
    dag=DAG(
        'Priority',
        default_args=args,
        schedule_interval=None,
        tags=["test_priority"],
        catchup=False,
    )

    FILE_TRANSFER_TO_VM=BashOperator(
        task_id='{0}'.format(var_file_transfer_to_vm),
        bash_command='gsutil -m cp gs://folders/files gs://otherfolder/',
        priority_weight=get_priority.fetch_value_from_cfg,  ##expecting this to pass context as argument         to function
        weight_rule='absolute',
        dag=dag
    )

I am fairly new to Airflow and Python. Can not figure out how to achieve this behavior. Any help/guidance is much appreciated.
Reason I need to do this is because we have around 1500 Dags and approx~ 10 tasks in each dag. Changing, updating Priority of each task is not feasible. Also, using global_priority for all tasks in each DAG not solving the purpose as we need to assign different values for different tasks.