On Gentoo I actively used github: download, then local build and install in ~/{bin,tools}. It was easy! I didn't even need ebuilds and did not think as this works :-)
Now I need several applications which are absent and will not be in official repositories of a distribution. For an example: 1. https://github.com/x2b/usbeject 2. xfce4-cpugraph-plugin I tried to define this as "some-package.scm" and build, but the first requires some magic with gexp, and for the second - it is unknown what for "use-modules". Finally, in the manual is just one stupid example "hello"! Help!!