Halogen now provides mobile apps for both iOS and Android.
I have not spent much time using the app yet, but I can already see how it would be convenient to capture performance journal notes. You might want to check it out.
It will require activation. Log into your account from a browser, click your name icon (usually your initials, unless you’ve changed it) and choose > APP ACTIVATION. It will give you a site code and number to activate the app.