In Google Ads, drill into any GShop campaign, then into the "Products" menu, you should see full reporting there.
If you are not looking inside of a single campaign, the "Products" menu will not appear.
So you have to dig into campaigns one by one, this reporting level does not span across like campaigns, like most other reporting levels do.
Also within Google Ads, go to "Reports" then begin building a Custom Report.
As you pick fields for your report, drill into the "Shopping Attributes" group of metrics.
For example, you can pull Item ID into your report, then grab other fields of interest and add them to your report.
In Google Analytics, drill into "Acquisition", then "Google Ads", then "Shopping Campaigns", it should default to your list of GShop campaigns.
Drill into any campaign, then drill into Level 1, 2, 3, 4 ,5 cats, when you click on your L5 cat, it'll show you you Item ID's in tat cat, with full reporting there.
Also in Google Analytics, you can drill into "Conversions", then "Ecommerce", then "Product Performance"...
Add a Secondary Dimension of "Campaign"...
Hopefully, your Shopping campaign names have something in their name that you can filter on, like the word "Shopping", so you can pull product level performance here.
There are other ways to skin this cat, but this will likely get you most of what you may need.
