Sales Automation App Banners are displayed in the gallery and shop. You can preview both the emails and banners by applying it to a test gallery.

After creating your app and assigning it to a test project from the gallery's Automations & Discounts tab, click on the three dots to the right of the app. From there, select Preview.

From the Preview window, click Create Preview for any of the phases of that particular app. You can send any emails from the app to your email address, or click View Gallery to preview the gallery with the banners.