We would recommend reading the Managing Feeds guide before continuing.
First, you will need to create a feed (or use an existing feed) that is assigned to each of the territories you'd like your products to show in.
In this example, the feed is assigned to all territories in the Demo store: US, UK, Germany, and Rest of Europe.
Next, add the language(s) for your feed.
Then click the Edit Feed's Elements and add all of the products that you wish to include in the feed. After, click the Close button and Save to see the products in the list view.
Once you're able to see the products, then select from the territory dropdown to the territory you'd like to edit.
Now, with the selected territory, click the Edit Feed's Elements button. A popup will appear, in which you can drag, drop, rearrange, add, and remove the products. Select Close and Save to keep the changes.
Repeat for each territory as needed.
If the front end of the store does not show the new updates, ensure to clear the Project Cache. Read more on Cache Clear Functionalities.