I am visually impaired, and tend to have my Pixel Slate set to its maximum display brightness. When I shut the device down and then start it up again, the display brightness on the login screen is almost unreadably dim for me. The same was true during initial device setup; I had to go into a pitch-dark room to read prompts on the setup screens, and even there I had serious eyestrain.

There are several independent ways we could improve this:

1. Make a brightness control available on the initial-setup screens.
2. Make a brightness control available on the login screen.
3. Remember the display brightness in use before shutdown, and restore that on startup. Clip at some minimum brightness to avoid making the display too dim to see at all if startup is happening in a much brighter place.