Currently, the theme’s RSS configuration (see src/pages/rss.xml.js) only allows visitors to subscribe to posts under src/content/blog/.
If you want to further customize which content on the site can be subscribed to, refer to the theme’s integrated @astrojs/rss documentation and Astro’s official guide.
If the official integration doesn’t meet your needs, you may consider using feed. Additionally, community-provided RSS Recipes are also worth checking out.
feed