Can I configure the app to show only products from the same collection?

Yes, you can limit the random recommendations displayed to products from the same manual collection of the current product. Just go to the Recommendation Tuning section from the preferences page:

Then, click the 'Configure random recommendations' button:

And select the 'Filter by manual collection' option (random recommendations must be enabled as shown in the previous screenshot):

Let's say, for example, that you're seeing a product page that is in a manual collection named 'Hats'. The random recommendations displayed will only be products from the 'Hats' collection.

In the collection filter only manual collections are used. Automated collections, like 'Newest', 'Best selling' or 'Low stock', are not used because they usually do not contain similar products.

Due to a limitation of the Shopify API, both published and unpublished manual collections are taken into account to build random recommendations by collection.

Please note that, if there are not enough products matching the selected criteria, the recommendations will be automatically completed using random recommendations.