Linux

It's an immutable/atomic version of Fedora: https://fedoraproject.org/atomic-desktops/silverblue/

My understanding is that the core system is immutable (read-only) and major upgrades essentially just swap out that whole layer. Updates are atomic, meaning the entire thing either succeeds or fails and you can never end up with a broken half-updated system. UI apps all run using Flatpak.

I've never tried it though!

It's an "immutable" Fedora, that is, the system comes as a read only image, kind of like how android works. Anything you do is "layered" on top of that image. This means you have to actually try to break it, because you can undo anything you did to break it by simply not booting with the extra layer(s).

You're encouraged to install in userspace flatpaks instead of system-wide rpms where possible, as system-wide rpms means adding a layer on top if the image as it is.

It's immutable (aka. atomic), which means the system files cannot be changed, even by root. System updates come as complete system snapshots of the core filesystem, and everything else exists in containers or filesystem overlays (user directory is still writeable). Containers and the user's home directory are unaffected by the updates, so the update process is typically much safer overall.

If an update does break something, you can easily do rpm-ostree rollback, and everything will be working again. On top of that, you can swap between versions with a simple rebase command (e.g. swap between Silverblue and Kinoite, Kinoite and Bazzite).