The result is purely static and the only redirection I make is from / to the welcome page; so using index.html as output would probably be enough to "just werk" with stuff like this or Github Pages/neocities.

Not sure about what you mean by preview, but here's how I do it: build the website, copy the output directory somewhere, run `sed -E -i 's#(href|src)=("?)/#\1=\2file:///absolute/path/to/dst/#g' dst/*/*.html` and open a page as file in my web browser.