How to identify traffic from Free Product Listings in Google Analytics?

Product links in the feed that FeedOps uploads to Google Merchant Center are tagged (using UTM tags) with feedops as the utm_source and google-free-product-listings as the utm_medium.

Note: For FeedOps users on certain plans are able to override the values of utm_source and utm_medium.

This enables web traffic to be differentiated in Google Analytics between traffic coming from FeedOps enabled Free Product Listings in Google, traffic coming from Google Shopping Ads, and all other traffic.