The package managers and official repos for most distros would be better thought of as lego blocks to build an OS from - they have no concept of OS and application separation, and splitting installation of an OS across multiple physical drives doesn’t really make sense.
The packages for Blender, steam, etc, and typical Userland apps are in these repos. The package managers are not the “Lego blocks” only. They are the utilities, user apps, and libraries you need. They are everything in one place. That’s a large point of Linux. Everything you need is in the repo.
Also, repos are distro related. You can’t use Fedora repos on Ubuntu. Originally you couldn’t use any distro’s repos on any other distro’s repos. With Ubuntu and its offshoots and arch and its offshoots, we’ve started to see repos grow to multi-distro but to say that they have no concept of OS is wrong. The whole reason there are distros is so that specific distros can configure things to their liking. This is why things like Debian and Ubuntu exist. It’s why OpenBSD exists. Again, a large selling point for Linux users is that all your packages are configured to be used with your distro.
Flatpak and Appimage are very specifically not what I am talking about. They aren’t typically supported by distros and don’t include distro-specific fixes/configurations for a lot of things.
Yeah, packages for things like Blender and Steam do exist in most distro repositories. But they make no distinction between packages that provide software like that and packages that provide core OS services + userland (systemd, pipewire, coreutils, cups, a desktop environment, and so on). What you want requires a distinction between those things.
See SteamOS, Fedora Silverblue/Kinoite + universal-blue, openSUSE Aeon/Kalpa, Endless OS, and possibly in future Ubuntu Core Desktop as examples of modern systems (or systems in development) that make use of traditional packages as the building blocks of the base OS, and then lean on application distribution methods like Flatpak or Snap to provide desktop software. Use of the distro package manager for software like Blender is explicitly discouraged by all of these.
Distro specific fixes and configurations shouldn’t be necessary as long as the OS provides what the application platform needs (desktop portals, audio server, display server, print server, message bus, etc) Flatpak doesn’t even prevent distro specific repositories if it’s really necessary either; Fedora ships with their own Flatpak repository in addition to Flathub.
You want better control of or isolated and relocatable end-user software installation, and it already exists - it’s just not being done at the traditional package manager level, and I haven’t heard about any development effort going towards changing that.
Those distros are different than what I am talking about. Those are immutable distros that preserve the preinstalled system base. It’s not at all what we’ve been talking about.
You’ve decided that it has to be the traditional distro package manager providing the solution - but that isn’t going to happen, because those have been designed to manage a single installation of interdependent software with no distinction made between core system libraries or services and end-user applications. The solutions to the problems that come from that - which also make it extremely simple to fix issues like the one you have using a single config file - led to the development of Flatpak and Snap.
Some traditional mutable distros also ship with Flatpak + Flathub configured out of box and present them alongside and with equal importance to their own distro-specific packages - e.g. Linux Mint, PopOS, Clear Linux, CentOS, and Fedora Workstation. And Ubuntu is pushing Snap. So they’re all unlikely to start putting work into enhancing their distro package managers to start providing the desktop software specific features that you want.
