No product feed yet? A published sheet of SKUs and cost prices is enough to get started.
Overview
A managed product feed is the right long-term answer, because it is already maintained by someone whose job it is. But if your cost prices live in a spreadsheet today, that will do to begin with. We read any CSV over HTTPS, and Sheets can publish one.
How it works
Publishing to the web turns a sheet into a CSV URL that anyone holding the link can read. Read that sentence twice: this is not your Google account's sharing settings, it is genuinely public, and search engines can find it. Put nothing in that sheet you would not put on a public page — product ids and cost prices only, no customer data, no supplier names or terms you would rather keep to yourself. If that is not acceptable, use a feed at an unguessable URL instead. If the sheet is not published, we get an HTML sign-in page back rather than a CSV, and the sync says so instead of failing quietly.
How to configure
One row per SKU. A column for the product id and a column for cost price excluding VAT.
File → Share → Publish to web, choose the single sheet, and pick Comma-separated values (.csv).
Copy the published URL — not the URL in your browser's address bar.
Paste it into onboarding step 1 and map the two columns.
Move to a real feed when you have one. The mapping step is the same.
