I can admit to force restarting windows during "updates" many times. After about an hour stuck on the same percent you loose faith it's doing anything and kill it. Never had an issue with this so far.
On Xbox one I believe there is a deep boot ROM that applies the updates, it looked like it staged it somewhere and then applied it. This I assume is so power outages for whatever reason mean it just restarts the process. originally it always used to update this way for me but now I have not seen it in a couple of years so they have made the process more streamlined or worked out I am on GMT and update during my night not Redmond's.
I would suspect that the update is designed around failure. If you plan it from the outset with worst case actions then it probably takes more steps copying or backing things up but it can cope with expected issues such as power failure during write to system files.
The Xbox one also has a force factory reset from USB recovery option, this works without the need for working video out and I believe uses the lower level boot ROM and not the OS at all.
You know errors happen between the controller and the chair so I am sure they have planned it to be idiot proof
The problem is you can't always recover the OS. There was a huge problem last fall with one of the xbox updates that they couldn't recover from
