>You can run snaps wherever you want

While that is technically true, snaps are very much build for ubuntu. For example it's sandboxing relies on apparmor meaning on distro without it such as archlinux, there is no confinement or security advantage.

Meanwhile flatpak is an actual distro agnostic containerized package management system using namespaces and seccomp available everywhere. Its infrastructure is also officially self hostable unlike snaps.