I have never used wallflower plugs before, but do prefer light scents, as you describe.
We do have diffusers for essential oils, though. Some are very small, and after dampening the pad inside with your scent of choice, you clip them onto your car vent or air conditioner vent, or clip them somewhere in the house.
If you didn't already have essential oils, it might be difficult to use them/change scents, but if you just use one for a while, or have a few essential oils (vs. fragrance oils.) they are quite nice, and rarely a heavy scent.
My dogs have never looked 2ce at them, though some might.
Love All Life, Thank You For Posting! :)