The term "shopping channel" can have several meanings. In the context of ecommerce, it is a website where consumers are searching for products and where merchants can advertise with product ads.
The most popular shopping channel is Google Shopping. Consumers who "google" a product will see a block of product ads on the Search Engine Results Page (SERP). These ads are served from Google Shopping, which is a campaign type in Google AdWords, Google’s advertising section.
The text ads and the organic results presented on the same SERP are not considered a shopping channel, even though they are a channel to sell through just as much as Google Shopping, because they are not product ads.