There sort of is, at least in Europe with Google's CSS providers. IIRC there's a few dozen aggregators and aggregators must have at least 50 merchants in order

There sort of is, at least in Europe with Google's CSS providers. IIRC there's a few dozen aggregators and aggregators must have at least 50 merchants in order to be a CSS partner. The products are shown as a carousel and can undercut Google by 20% due to tax/competition reasons. I'm not fluent on the underlying reasons- the results are also on Google shopping.