How can I go about detecting the pressed volume button on the side of the device?
you might want to try the settings extension
Taifun
Trying to push the limits! Snippets, Tutorials and Extensions from Pura Vida Apps by 
Taifun.
with your extension
https://puravidaapps.com/settings.php
is it possible to intercept / detect if the volume button is pressed?
I would like, once the event has been intercepted, to call a procedure …
this is not directly possible, but you can use a Clock component and check the 3 volume properties regularly if they changed...
Taifun