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Hello

you can try this code. WARNING, probably you should tweak it.
thanks, Alex

add_filter( "wpo_custom_product_search", function($results,$query_args,$term) {
 global $wpdb;
 $term = esc_sql($wpdb->esc_like($term));
 $results = $wpdb->get_col("SELECT ID FROM $wpdb->posts WHERE post_type='product' AND post_status='publish' AND post_title LIKE '%{$term}%' ORDER BY post_title LIMIT 25");
 return $results;
},10,3);

Updated version (+ SKU)

add_filter( "wpo_custom_product_search", function($results,$query_args,$term) {
 global $wpdb;
 $term = esc_sql($wpdb->esc_like($term));
 $results = $wpdb->get_col("SELECT ID FROM $wpdb->posts WHERE post_type='product' AND post_status='publish' AND post_title LIKE '%{$term}%'  
                           OR ID IN (SELECT post_id FROM $wpdb->postmeta WHERE meta_key='_sku' AND meta_value LIKE '%{$term}%' )
                           ORDER BY post_title LIMIT 25");
 return $results;
},10,3);

you’re welcome