This is amazing. I wonder if it's possible to integrate it with a static site generator (Hugo Jekyll pelican etc) so I can get the best of both worlds?

There's https://github.com/jez/tufte-pandoc-css which integrates with Pandoc.

I use it for my blog that features margin notes from time to time: https://blog.kdheepak.com/

Though I had to write a lua filter to make the Pandoc margin notes work appropriately :)