Communication between Android app and Python backend
WebSocket should be the interface of choice.
The python script should expose a WebSocket end point . The mobile app can establish a connection to the WebSocket. The socket can act as a bidirectional channel where the app can send and receive data and the python script can do the same. 
Firebase : The app could publish the user inputs to a Firebase topic which the python script listens to. The script can process the inputs and publish to the same channel that the app would listen to. More like a P2P chat
I wrote an app with Android Studio and want to send the data that the user enters to my back-end Python script. This should constantly process the received data and send back the evaluation.
Does anyone have an idea how this could work?
thanks in advance