Squarespace Commerce CSVs have the same holes. You do not need an extension.

Blank SKU, $0 price, no hosted image URL, two rows sharing a SKU. Export the product CSV and check it in the browser.

Open the CSV check

How

1. Squarespace → Commerce → Inventory → import/export (CSV with Title, SKU, Price, Hosted Image URLs).
2. Open csv-check.html and drop the file. Nothing is uploaded.
3. Fix the rows that cannot sell. A ranked Monday list of 20 is the Store Audit (USD $149) — email the same CSV to info@shopgaps.com.

ShopGaps is not a Squarespace extension and does not connect to your site. Wix Stores: wix.html. WooCommerce merchants who want an on-site plugin can use Catalog Audit.