With Iris theme you get an option to offer a specific product directly in the shopping cart.

You can use this to cross-sell a product or even a service that might be valuable to your audience regardless of what they purchase. It could be a t-shirt with your brand logo or a gift wrapping.

To set it up head on to “Theme Settings->Cart”. Enable cross-sell feature and select the product you want to display. You can also add a heading to encourage an action.

In case of a gift wrap product or certain other cross-sell products you may not want to have the product displayed on your product listing and collections. To hide any product you can use the “hide-product” tag.