CachyOS and openSUSE have you covered with btrfs and snapper pre-configured to take snapshots before/after doing potentially damaging things (and, of course, you can make them manually, whenever the thought occurs to you that you're entering the "danger zone"). You can boot into a snapshot directly from the boatloader, then rollback if you need to.

Immutable distros just one-up that by trying to steer the system in a direction where it can work with a readonly rootfs in normal operation, and nudging you to take a snapshot before/after taking the rootfs from readonly to read-write. (openSUSE has you covered there as well, if that's your thing; it's called MicroOS).

Both of those distros use KDE by default, so the value-add of KDE having its own distribution is basically so they can have a "reference implementation" that will always have all the latest and greatest that KDE has to offer, and showcase to the rest of the Linux world, how they envision the integration should be done.

If I were to set up a library computer or a computer for my aging parents, I would choose openSUSE Leap Micro with KDE, as that would put the emphasis on stability instead.

There's also https://getaurora.dev/ - another immutable KDE-based distro. I've been using it as my daily for ~half a year now. It just works.