Yes, it is possible to build reviews and star ratings functionality for CMS (Content Management System) items without it being an eCommerce product. Here's a detailed explanation of how you can achieve this:

1. Choose a CMS platform: Select a CMS platform that supports custom fields and extensions/plugins. Popular CMS platforms like WordPress, Drupal, and Joomla offer this flexibility.

2. Install a rating/review plugin: Look for a rating/review plugin that is compatible with your chosen CMS platform. For example, if you are using WordPress, you can use plugins like WP Product Review, WP Review, or WP Customer Reviews. These plugins allow you to add star ratings and review functionality to any content item on your website.

3. Create custom fields: If your chosen CMS platform supports custom fields, you can create custom fields for your content items to store the rating and review data. For instance, in WordPress, you can use plugins like Advanced Custom Fields or Toolset Types to create custom fields for your content items.

4. Add rating/review functionality: Once you have installed the plugin and created custom fields, you can start adding the rating/review functionality to your CMS items. This can be done by adding the necessary code or using the plugin's built-in features. The exact implementation process will depend on the plugin you choose.

5. Display ratings/reviews: To display the ratings and reviews on your website, you can use templates or shortcodes provided by the plugin. These templates or shortcodes can be added to your CMS item's template file or content editor.

6. Customize the appearance: Most rating/review plugins offer customization options to match the appearance of the ratings and reviews with your website's design. You can modify the CSS styles or use the plugin's settings to customize the appearance of the ratings and reviews.

7. User interaction and moderation: Ensure that users can submit ratings and reviews for your CMS items. You may need to configure the plugin settings to allow user submissions and set up moderation features to review and approve the submitted content.

By following these steps, you can easily add reviews and star ratings functionality to your CMS items without the need for an eCommerce product. Remember to choose a reliable and well-supported plugin that suits your CMS platform and requirements.

References:
- WordPress Plugins: https://wordpress.org/plugins/
- Drupal Modules: https://www.drupal.org/project/project_module
- Joomla Extensions Directory: https://extensions.joomla.org/