Cut 1 — spend versus return, per product
Sort by spend descending. The products at the top with no conversions are your fastest saving.
Cut 2 — impressions versus clicks
Products with impressions and no clicks have an image or price problem. Products with no impressions have a feed or eligibility problem. Different fixes entirely.
Cut 3 — products with zero impressions
The part almost nobody looks at. In most catalogues it is a large share, and it is invisible in campaign-level reporting.
Then label by tier and let the campaign structure act on it. Structure that follows profit.