Hi @CC_ArdMoor ,

Thanks for being a part of the community.
To learn more about how to set up a Cross Sell Flow, I would suggest reading this help article: How to create an upsell or cross-sell flow. It also goes over the usefulness of Product feeds.

A dynamic product feed can be set to generic products that display on all visitor activity or to that Profiles activity. Once the Feeds are set up, when previewing the template, the the product block will populate to the Feeds definition. 
 

 
Here is the guide, How to use product feeds and recommendations, for more information on Product Feeds.

Lastly, for your situation here is an example scenario and setup:

Your options are to filter the content at either the Flow level, or at the Template level. 
 
For example, if you filter content at the Flow level, that means recipients will go down different Flow paths depending on which product tags are in the trigger splits like this:

 
Alternatively, if you choose to filter content at the Template level then there would be a single Flow path like this:

 
But that single email template would have conditional logic to Show/Hide content depending on the triggering event data like this: