Ironically, the "about" and "projects" links on his blog are broken (which I guess has been generated by a static site generator).
Anyways, I've just fixed it (might take some times until the cache expires, don't bash me over again ;-), thanks for the reminder!
The default Jekyll setup does indeed rely on some implicit theming, which is not very convenient.
If I were to already have the artifact files locally I wouldn't commit them in git and push to GitHub, I'd upload them straight to S3/Neocities/whatever. The whole point of Pages is to push some source material and have some CI/CD do the build and deploy.