Well HABPanel is a single page application. So I assume you could create a custom widget and place it anywhere (even where you won’t see it) and have it fire toasts with one of the toast libararies.
But how to load that library? There are some topics about this already. Have a search for lazy loading in this forum category. I can’t find it right now but it is somewhere.
Next step would be to transport data to that widget, to have it toast it for you. I could even think of a String item, that holds a list of your toasts and your widget will remove them as it consumes and displays it on the screen.