Adding an autonomously powered buzzer is a good idea: it'll help to find the Tello when it landed somewhere after its battery is exhausted. But the buzzer adds extra weight and shortens drone's fiight time.
And I don't like the battery hanging on one side of the drone - it breaks the drone's balance.
Любая программа должна на чём-то выполняться, то есть к Tello нужно будет приделать микроконтроллер, которому требуется питание - а всё это добаляет вес и уменьшает и так небольшое время полёта.
Any program needs a device for its running. So a micro-controller with a battery should be mounted on a Tello - and this will add additional weight and shortens the flight time, that it's not very long.