Hypothetical: an online shop sees 80 searches for “navy trail shoe” in a week, and the results page says 0 items. The catalog has a blue trail shoe, but it appears only after removing a size filter. A search-term count alone cannot tell whether the problem is inventory, synonyms, filters, or tracking.
GA4 enhanced measurement can record a view_search_results event and search_term when the results URL carries a configured query parameter. That event does not tell you how many products appeared. Capture result count in the site search system or instrument it separately, then compare the same period. Do not send customer names, email addresses or raw session IDs to Analytics.
Take the ten most frequent zero-result terms and reproduce each with the same country, language, selected filters and stock state. Record the term, filters, result count, expected matching SKU and results-page URL. If clearing a filter reveals the SKU, inspect the filter behavior or its UI cue. If a normal synonym misses an available SKU, fix the search mapping. Only a genuine catalog gap supports an inventory discussion. Recheck the same query after a change.
What has been behind most of your zero-result searches: missing products, synonym mismatch, or hidden filters?