I’m wanting to create a sound that plays over a media player when the system is restarted. I see that you can use shutdown and start in the Home Assistant Trigger under Automation. Does shutdown occur during a restart?
This could be added as a trigger but there is no guarantee to start up again 
so it can lead false expectations
trigger:
- platform: homeassistant
event: start
start would allow me to fire an event if the system has started, which I already to for a few things, but I’m thinking that if I want to announce that home assistant is shutting down for a restart, I would just need to create a script for it, then put a button on a “control panel” tab in the UI, and that way I could also incorporate an abort button just in case it’s bad timing for everyone else in the house.
But if the restart event (assuming it exists) is fired, i don’t think you can abort it now.
What about, creating a script/automation controlling a timer and announcement and cancelling the timer if someone aborts it, otherwise call restart if timer gets zero.
See this :