This isn't actually a good analogy, because Flatpak was designed from the ground-up to be vendor-neutral. For example, the "runtimes" that provide the virtual Linux distribution for applications to work in are built with packages and tools from the Linux Foundation's Yocto project. Similarly, the code is deliberately hosted on GitHub with no CLA so that all contributors are on neutral ground (there is at least one Debian developer involved). The main developer is a Red Hat employee, and could have used Fedora or CentOS packages, tools and infrastructure, but explicitly chose not to do that, to protect Flatpak's neutrality. He also builds Flatpak for Ubuntu, Arch and other distributions, so that people can freely use Flatpak on their systems even where it isn't currently supported by their distribution of choice.