On the blogdown demo site we link to how to render xaringan type Rmd files:
https://blogdown-demo.rbind.io/2017/09/06/adding-r-markdown-documents-of-other-output-formats/
I will say I have found it easier to store my presentations in a separate repo then link to them from my site though. But, you can actually knit to moon reader from within your blogdown file structure, working in a directory other than contents/post.