For those brave enough to attempt this on their own, it is actually rather simple. Beware, this may brick your phone. However, if you follow this guide, the risk is relatively low. This will also factory reset your phone a couple times, so make sure everything you want is backed up off the device. Only purchase an unlocked device. If you know:
1) How to open a command prompt and what “cd” does,
2) What an environmental variable is,
3) and/or you can follow directions, you can set it up yourself.
Here is a set of instructions/links that I use that are a bit easier to follow than GrapheneOS’s website (https://grapheneos.org/install). For the record, they discourage unofficial installation guides. Graphene’s preference is for the web installer (https://grapheneos.org/install/web) that runs some sanity checks during the process. According to them, it is impossible to hard brick a phone from the web installer. And if you happen to soft brick it, I can help you out, I’ve recovered over a dozen devices to date. The web installer uses the WebUSB APIs which are currently only supported by Chromium browsers (Google’s Chome, MS’s Edge, Brave Browser, etc). It gives the user a secure dialog prompt to safely select their Pixel in fastboot mode. It only requires the appropriate fastboot USB drivers. The rest of the installation is simply clicking a few buttons and waiting. This means you can flash GrapheneOS from another Android device with a USB-C port as it’s simply using the browser storage, browser cache, and WebUSB.
If you want to live wild and use an unofficial guide that may brick your phone without the sanity checks, here’s the instructions I use:
1) Install Android SDK platform tools using this guide that is current and has directions for Windows, Linux, and Mac. https://www.lifewire.com/android-debug-bridge-adb-4149410
2) Download and unzip the correct version of Graphene for your specific phone. Make sure these are from the Stable Channel and it is the factory *.zip file, not the *.zip.sig or the ota-update.
https://grapheneos.org/releases#stable-channel
IF YOU CHOOSE THE WRONG VERSION HERE, YOUR DEVICE WILL HARD BRICK AND THERE IS NOTHING I, OR ANYONE ELSE, CAN DO TO HELP YOU
3) Download the Windows drivers for Pixel phones through Windows Update’s “optional updates.”
4) Enable OEM unlocking. Enable the developer options menu by going to Settings ➔ About phone and frantically tapping on the build number menu entry until developer mode is enabled. Next, go to Settings ➔ System ➔ Advanced ➔ Developer options and toggle on the ‘Enable OEM unlocking’ setting. Sometimes this is grayed out and a factory reset will enable it. But likely if it is grayed out, the phone is not unlocked. If after doing a factory reset the OEM unlocking is still grayed out, perform another factory reset and go through the G start up procedure, but be sure to enable wi-fi and connect to a network.
5) Make sure the phone is fully updated. This is in Settings ➔ System ➔ Advanced ➔ System Update Settings.
6) Unlock the bootloader. Turn off the phone, then turn it on by holding both volume down and power to get into the bootloader menu. Connect it via USB to your computer. Open a command prompt on your computer and type “fastboot devices.” It should list the device as connected. Then type “fastboot flashing unlock.” Hit the volume up button so it displays that you want to unlock the bootloader, then hit the power button to confirm. Do not unplug the USB until you press the power button to start the phone up (best to just leave it plugged in from here on).
7) Boot up the device again. Go thru the setup again.
8) Open a command prompt in the directory of the unzipped file you download from Graphene. The folder you should open it in will have a file called “flash-all.bat” in it.
9) Type into the command prompt “adb devices”. This will be followed by a pop up on your phone asking to “Allow USB debugging.” You should allow this. If the command prompt lists your device, then you’re good to go. Type “adb reboot bootloader”. This will restart your phone into the bootloader interface again
10) Type into the command prompt “flash-all.bat”. This is installing Graphene. Phone will restart a few times into the bootloader interface, then to the fastboot interface, then finally back to bootloader and the command prompt will tell you to press any key to exit. Press a key. I have had this step fail once. I just tried it again and it worked.
11) Type into the command prompt “fastboot flashing lock”. Hit the volume up button so it displays that you want to lock the bootloader, then hit the power button to confirm. Do not unplug the USB until much after you press the power button to start the phone up. Best to wait until you’re in the setup screen for the phone
12) Go thru setup again, but this time for Graphene (much quicker)
13) Disable OEM unlocking. You will have to enable Developer Options again to do this.
14) You are done!