Hugo is powered by Go, Jekyll by Ruby, Gatsby by React. Gatsby lets you use GraphQL to flexibly render your content (a special listing page for instance). So if you like either React or GraphQL or want to learn them, check out Gatsby!
Robert Myles wrote a tool for .Rmd to .mdx, introduced in the blog post From R to Gatsby. Source of Robert Myles’ website.
Example of other websites:
Not R related but interesting read: Migrating to Gatsby by Scott Czepiel.
Last point, I read in a post on RStudio Education blog that Gatsby is part of what powers the course framework created by Ines Montani.