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Agentic buying: what changes for Portuguese shops when the AI buys on its own

In the US, AI assistants already complete purchases inside the conversation. In Europe the shop window arrived, not the checkout. What already works in Portugal, where the price, stock and delivery data come from, and what to prepare now.

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First, the term: agentic buying is a purchase started or completed by an AI assistant on behalf of whoever asks. The user says "I want an upright vacuum for under 200 euros delivered tomorrow" and the agent compares, chooses and, in the markets where that is already possible, completes the order inside the conversation. This article says what already works and where, where the data the agent reads comes from, and what a Portuguese shop should prepare now, with sources and dates throughout.

What already exists, and where (August 2026)

The transaction inside the chat is real, but geographically confined. The state of play, market by market:

Market by market, August 2026

Google: agentic checkout in AI Mode launched in November 2025, United States only, with Wayfair, Chewy and Shopify shops. AI Mode itself has been live in Portugal in Portuguese since October 2025, with product panels, prices and buttons: the shop window arrived, the counter has not.

Sources: blog.google, openai.com, Search Engine Land, Microsoft Advertising and PayPal, on the dates cited.

The honest reading for Portugal: the shop window arrived, the checkout did not. And that is exactly why the moment is good: the race for presence in the window is open and almost nobody here is running it.

Where the price, the stock and the delivery come from

The agent does not read your site like a human: it reads structured data. Three layers, in order of importance today:

  • The Google Merchant Center feed. It feeds the Shopping Graph (more than 50 billion listings, with 2 billion updated per hour) and it is the door to AI Mode. Free listings are eligible: you do not need to buy advertising to appear. The minimum: GTIN, brand, category in the Google taxonomy, availability and shipping, with price and stock matching the page, otherwise the listing is disapproved. In May 2026 the Merchant Center gained six conversational attributes designed for AI Mode; almost no Portuguese shop fills them in yet.
  • The schema on the product pages. Product and Offer with OfferShippingDetails and a returns policy: it is what validates the feed and what the engines without a feed can read.
  • The assistants' own feeds. OpenAI published a product feed specification (registration at chatgpt.com/merchants) that accepts refreshes as often as every 15 minutes, with inventory and delivery estimate fields. Ingestion is US-first with an international waiting list. While it does not open, the most useful figure in this market applies: a March 2026 study of 43 thousand products showed that around 83% of the products in ChatGPT's carousels come from Google Shopping's organic top 40 (Search Engine Land). Translated: optimising the Google feed is optimising ChatGPT, today, from Portugal too.
  • 83%of the products in ChatGPT's carousels come from Google Shopping's organic top 40
  • 43 thousandproducts in the March 2026 study
  • 15 minthe most frequent refresh OpenAI's product feed specification accepts

The study gives around 83%: an approximate figure. Sources: Search Engine Land, March 2026 (the carousel study); developers.openai.com (the feed specification).

And the advertising in the middle of this

The same shop window has paid space. In Google, the ads enter AI Overviews and AI Mode automatically from the Search, Shopping and Performance Max campaigns that already exist, with no separate campaign. In ChatGPT, advertising arrived in the United Kingdom in June 2026 and OpenAI announced to European users, on 15 August, that it arrives in the EEA that same month, non-personalised, on the free plans only. In the other direction, Claude and Perplexity have stated they will not have advertising. The practical consequence: an AI answer now has two columns, the earned one and the bought one, and measuring one without telling it from the other is fooling yourself.

What to prepare now, in order

What to prepare now
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To close

Agentic buying is not a forecast: it is working, with millions of transactions, on the other side of the Atlantic. In Europe the shop window arrived first, and shop windows are won with data: price, stock and delivery legible to machines, measured week by week. It is work a Portuguese shop can start this week, and it is what we do.

Frequently asked questions

Main sources: blog.google (agentic checkout, Nov 2025; AI Mode in Portugal, Oct 2025), openai.com and developers.openai.com (Instant Checkout and the feed spec), Search Engine Land (the carousel study, Mar 2026; the checkout pullback, Mar 2026), Microsoft Advertising (Copilot Checkout, Jan 2026), PayPal (Perplexity Instant Buy, Nov 2025). Dates cited in the body of the text.