I believe it should still work, as alarms trigger for me even if my phone updated overnight or I put it on the charger dead before going to sleep, but I’ll have to test it

As the linked screenshot shows, you have the option to choose between shutting down and rebooting. There is no need to explain the difference to me, I demonstrated that the thing you want to do is possible.

You can, see my other comment: https://feddit.org/comment/3001525

That’s not what I mean, I’m talking about the Shortcuts app:

There is a shortcut action to shut down the phone which you could trigger with an automation, I suppose.