Hiya,
Just wanted to share with you my solution for missing notifications/actions for Duet upon change of print status.
I've builtin pushbullet/pushover/email support into it. You can also define some system commands/scripts to execute after status change.
Please have a look and feel free to use it, grab the code do whatever you want.
I've precompiled sources for Linux/OSX/Windows.
https://gitlab.com/Toriniasty/reprap_notify
Latest version: https://gitlab.com/Toriniasty/reprap_notify/-/releases