"dnf update" considered harmful

I'm sure you have, but this isn't about what a skilled administrator can do with tools and planning, this is about what completely dumb automation can do reliably and at great scale when there is no one who can fix things if they go wrong, so that even a minor error will effectively brick machines for some number of people. There is a continuum of more reliable to less, with active/standby partitions to upgrades from a special single-user mode to live upgrades with testing and tool support or just copying new files over old, some have more possibilities for failure and require more admin intervention than others.