Browsing How to rebase to Fedora Linux 38 on Silverblue – from Fedora Magazine I just discovered that
Fedora Silverblue is a new variant of Fedora Workstation with rpm-ostree at its core to provide fully atomic upgrades. Furthermore, Fedora Silverblue is immutable and upgrades as a whole, providing easy rollbacks from updates if something goes wrong.
Just wondering is there anything Debian based. And of course someone else already asked this (on Reddit) and other people curated a list of immutable distributions. So the answer is EndlessOS and Vanilla OS.
Silly me, I bought a laptop for my father-in-law with EndlessOS, finding it very solid!