After updating a Pixel 2 to Android 10, I experienced all the mentioned problems. I tried all the recommended restarts and safe modes.
The battery drained so fast that one afternoon it went dead flat. Just the blinking battery pic at zero%.
Hours later I charged to full capacity.
After turning the phone on, most of the issues have gone away, and I am enjoying the benefits of 10.
Not sure which part of the process worked. Just thought I'd share.