You can use the headphones (wired or bluetooth) to control some function of the app, for example during automotive recording you can press a button on the headphones and have a flag on the graph at the time of button press to remember the time when an event occured. You can use commercial headphones (with

DIY oscilloscope attenuators using 3D printed method.

Budget and quality BAR/PSI Absolute Sensor ready-to-use for automotive applications.