Quarto makes PDF files, books, slides and websites, and it runs code. To do so, it installs Pandoc, Deno, Sass, esbuild and Typst, which take more than 600 MB. Many projects use Quarto for one thing only. They build a documentation site from Markdown and from their code.
smalldocs does that one thing. It is one Python package, and it installs from PyPI.
smalldocs needs no Sass compiler, because of how Bootstrap 5.3 themes work. A Bootstrap 5.3 theme sets its colours and fonts as CSS variables. smalldocs takes the CSS files that Bootswatch publishes. Then it lays out the page with a stylesheet that uses only those variables.