Allow gauge/value notifications to break through do-not-disturb
Gauge/value notifications are usually used for things like audio volume and screen brightness changes. I find that enabling DnD and losing these notifications is pretty annoying, as I really like the feedback when pressing the volume or brightness keys on the keyboard.
This would have to be done with care, though: it's possible that some app might be using gauge notifications for something else, which should not be allowed to break through DnD. I can't really think of a possible (even theoretical) example, but that could just be a lack of imagination on my part.
I'd like to avoid a user preference for this, but maybe that's unavoidable.