Howdy @Manolo!
Good question.
You can't use flexdashboard inside distill natively, but you can "link" to other content from distill.
For example, I have some slide decks hosted on distill by creating and adding arbitrary other content in a "static" folder.
For example Slide Deck which is located at:
.../static/slidesand you can see the content on my GitHub.
In this example you can add knitted flexdashboard and link to it from the blog.