For a couple of years now, macOS has an RO System volume image, and then mounts an RW data volume on top of that, similar to how overlayfs works on Linux. That system volume isn't modifiable. If it is, then the system won't boot. So I'd say it's a little bit immutable.

https://eclecticlight.co/2021/10/29/how-macos-is-more-reliab...

For most users, including many developers, SteamOS absolutely can be general purpose.

There are two main "daily driver" usability issues on SteamOS by default if you need to do technical work:

- Limited software availability via the flatpak repositories.

- Not being able to install certain programs as easily without needing containerisation of some kind (if that even solves the problem in some cases).

Distrobox solves a good amount of both issues on SteamOS, for coding work at least. Slap a virtual Ubuntu on and you're off to the races.

How would you define an immutable distro that would exclude macOS with SIP?

And steamOS is totally a general purpose OS, it’s just got a non-general purpose frontend it defaults to.

> SteamOS is not a general purpose OS

Uh... yeah it is. Have you ever switched it into desktop mode? I haven't pushed my Steam Deck as hard as my daily driver Linux system, but I've done all sorts of fun things on it like run a web server and write new Python scripts directly on the device. You can hook up a keyboard and mouse and monitor and use it like any other desktop Linux environment. It's basically just an Arch distro with KDE and some extra stuff on top to make it easy for people to run games.