pkgsrc is a framework for building third-party software on UNIX-like systems. It currently contains over 17000 packages.
Pro Offering tooling for backporting fixes
Backporting fixes can be done by cherry-picking updates from a newer branch (pkgsrc is released every 3 months) and creating a package. Sometimes bugs need to be fixed for production and there is neither a fix in newer pkgsrc nor the softwares upstream. So pkgsrc has tools like pkgdiff, mkpatches, etc. that help with developing patches and building binary packages from that. A bit of documentation about that process can be found here.
Pro Both binary packages and source build possible
Fast software installation is possible by using binary packages. It's also easy to build from source which allows for different compile-time options (like different UI backends) as well as gaining access to pre-release versions of software in certain cases.