There are some goodbye threads that include live reactions from the person taking the SN - avaruus comes to mind, as well as アホペンギン's attempt.
I also read a detailed thread about a livestreamed experience, but I don't remember the names involved anymore. (a related name (?) was something like moonshine, I think? It was before my time, I'm sorry.)
The reactions can vary, and these types of posts are the closest references we have for those final moments.
I'd suggest trying to find threads like that if you'd want to learn more.