Install DutyLookout
DutyLookout installs from the Shopify App Store, so the permission prompt and billing stay inside your Shopify admin where you can audit them. It reads your products and writes back an HS code you approve (or let it auto-approve); it never touches customer data. No monthly fee — your first 25 classifications in each 30-day billing period are free.
Installing takes one click from inside your Shopify admin — you will not be asked to type your store address anywhere.