As far as I know you can't access the flashlight from Nova Activities, or Actions, without first downloading an app that includes this toggle. I use Power Toggles, so I can have the flashlight toggle even in the lock screen.
Thanks. I'm already using Power Toggles, but notice a delay in the toggle turning the flashlight on / off at times. Hence why I wanted to use the activity instead.
I don't think there's an activity for the flashlight. It's just a toggle in the quick settings so Nova can't reach it. Let me know if you find a workaround so I could use it as well