I have a Google store online XL. I am interested in what you have to say. I just got mine but due to commitments have not had time to sift through all of the information available here. I've had Nexus 4 & 5x rooted w/custom roms but Idon't feel comfortable diving into the XL yet. Most of all I am afraid I will miss some thing on page 20 of a multi-page thread that will cause me pain later on.
Thanks
This thread will be the guide you'll want to follow, which assumes you have a Windows PC to connect the phone to:
https://forum.xda-developers.com/pixel-xl/how-to/guide-how-to-unlock-root-flash-pixel-xl-t3507886
Here is my own condensed version of it:
You'll first want to download and install the SDK for the correct tools from here:
https://dl.google.com/android/repository/platform-tools-latest-windows.zip
Then you should probably turn on USB Debugging from Developer Settings on the phone, and connect it to your computer. Check to see if it is talking to your phone correctly by opening a command prompt from the folder your fastboot/ADB installed to (typically C:\Program Files (x86)\Android\Android SDK\Platform-Tools\) and type: adb devices and hit enter. You should get your device listed.
Next, type adb reboot bootloader and hit enter. Your phone should reboot to the Android guy laying down with his chest open.
The following step ERASES the whole phone!!!
Now type fastboot flashing unlock.
This will unlock the bootloader. I would never recommend re-locking this again.
Now type fast boot reboot and your phone will be back to the OS, but if you did it right you get a warning each time you boot up before the boot animation.
Now you can install TWRP. This is easy. Download both the .IMG and the zip from here and put the IMG in that fastboot/ADB folder and put the zip on your phone in the download directory:
https://dl.twrp.me/marlin/
Make sure you get the ones that say RC1.
Keep the phone connected after downloading those files, type adb reboot bootloader again to get back to the Android guy.
Then type the following and hit enter: fastboot boot twrp-3.0.2-0-RC1-fastboot-marlin.img
This will boot up TWRP and get you to the menu.
Go to install and browse to the zip you put on the phone and install the TWRP zip. It will do it's thing and complete. You can then reboot to make sure you get into the OS okay. You can disconnect the phone from the PC since you can do everything from TWRP alone.
Now you can root. Just DL the SuperSU zip found here on your phone and put it in the download directory again.
https://download.chainfire.eu/1021/SuperSU/SR3-SuperSU-v2.79-SR3-20170114223742.zip
You can now do a restart on your phone and once the screen goes black HOLD the volume down button. You should see the android guy again. You can let go, then cycle thru the options with the volume key until you see recovery on the right in red. Press power to get to TWRP. Then Install, search for SuperSU zip you downloaded, install and reboot.
It will reboot on it's own several times. Just wait a few minutes until you get to the OS again. Congrats you're now rooted.
You can get the kernel of your liking and install the same way as you did with SuperSU.
Hope this helps.