You can set your home screen to use app drawer and change the left screen to app vault, Google discover, or none.
App drawer + Google discover puts the home screen fairly similar to stock pixel launcher, but definitely not as flexible as third party launchers.
Silly question, but you downloaded the right package for flashing right? After flashing, it did take me like 15 minutes of black screen before it started booting up.
You should be able to enter fastboot and try again.