Minify is enabled by default. It obfuscates, de-comments, and compresses JavaScript files, and compiles SASS and SCSS into CSS.
That means that right from the get-go, you can use SASS/SCSS, no setup required, even in barely's live-mode!
For configuration options, see the documentation.
One important thing to keep in mind is that if you want to use JS-functions from your HTML/jinja files by means of onclick=""
event attributes, you will want to deactivate JS-obfuscation.