Official docs
The “Help” section of the Beyond PangoScript editor has lots of the key low level info on PangoScript.
PangoScript examples
https://wiki.pangolin.com/doku.php?id=examples:pangoscript
Accessing PangoScript
Things like MidiDevices have direct access to PangoScript that relates to them.
You can also create PangoScript directly in the right side PangoScript tab