He definitely is using Emacs for most of it. He authors his posts in org files, and uses ox-hugo to export to Hugo.
I do something similar for my blog, except Pelican is my backend.
https://andreyor.st/posts/2022-10-16-my-blogging-setup-with-...
Re:Emacs GUI Library
by sureglymop on Wednesday July 12, 2023 @05:09AM
(#36692056)
Interesting. I think I must've seen the same post when he posted it.
Nowadays I just use Pandoc to go from markdown (with extras) to html.
[1]: https://andreyor.st/posts/2020-06-05-managing-background-pro...