Perhaps I should have been more clear. My apologies. I wanted to draw attention to the fact that -in the case of Fedora Atomic- layering remains a necessity (for most users). This thread goes over it in more detail.
flatpak
Technically speaking, the flatpak format isn't even as limited as some make it out to be. For example, software like Bottles have offered CLI/TUI functionality through it. But Flathub, its most popular storefront, does put a limitation on submissions. Which means that it's effectively not even competing with other package managers that (conventionally) try to offer a broader set of software.
Furthermore, even if the flatpak package exists, not all functionality is retained. For example, the situation around native messaging is still a mess. This prevents e.g. your flatpak browser from communicating with your locally installed password manager. While a(n ugly) workaround exists, it’s quite maddening that it hasn’t been resolved in all these years 😅.
distrobox/toolbx
This is actually a mess. See this comment elsewhere under this post for a bit more elaboration.
Yeah, NixOS is excellent. But, for
nix(or close enough) to be the future, an upgrade path should exist for other distros. But, for some reason, I don't really see any such efforts. Like, where are thenix-variants of other distros?FWIW, Bootcrew has created
bootc-variants of many other distros. And, even before, both Endless OS and GNOME OS offered examples of non-Fedora distros withostree.