I don't have an Ardunio Nano 33, to do tests.
In this Community there is information about this type of Arduino.
https://community.appinventor.mit.edu/search?q=Arduino%20nano%2033
I think the best option is that you learn to send random numbers from Arduino to the application, and observe those numbers in a Label, when you get it you can use the Chart component or the extension to display it graphically.
Remember that you must set Bluetooth permissions in the new Android.