The good news, for me anyways. All's running smoothly so far w/o any noticable impact on battery life or performance. Can't say it was worth the wait but at least it's done and over with... Dark mode was my biggest want.
I have a Huawei P20 Pro CLT-L04 in Victoria, BC
The update downloaded sometime in the last few days.
I had to get off the WiFi because the Telus server was blocked
But then the RESTART button worked and a few minutes the install was complete.