Solus is a independently-develop operating system for desktops, using its own desktop manager called Budgie, which currently relies on the GNOME Stack. Solus has its own software repositories with up-to-date packages, but it also offers access to some closed-source software projects, such as Google Chrome through its in-house built package manager. The collection of third-party apps offered there for Solus users is growing with each new major update of the operating system, but it would appear that the Solus Third Party system is far from robust, nor reliable. That’s why Solus needs to implement a third-party tool to distribute these kind of apps that aren’t available in the repos, and they are choosing Flatpak.