This blog goes over how to install CalyxOS — a custom Android ROM for (somewhat ironically) Google's Pixel phones. It's built with "Privacy by Design"; minimizing tracking done by phone manufacturers, cell providers, ISPs, advertising companies, etc. That being said, it's not as extreme as alternatives, notably GrapheneOS, and seeks to maintain a balance between usability and privacy. You can check (and contribute) app compatibility here.
---Backup
You will loose all of your data so backup stuff you want to keep. You won't be using Google to backup/restore once you get CalyxOS installed, so you're best bet is probably to transfer files directly to your computer. You can do so by enabling "Data Transfer through USB" so your files can be viewed & copied from your PC File Explorer.
Unlock Bootloader
Go into your device's settings, About phone,
and down to Build number. Spam the button 10
times until you get developer. Then, go back and to
System > Advanced >
Developer options and enable
USB debugging and
OEM unlocking
Update Drivers
Download the
Google USB Drivers
and extract the files somewhere on your PC. Then, showdown
the phone, press and hold the power and volume down until
the bootloader (black screen with a red triangle) appears.
You can then connect the phone to your PC if you haven't
already and go to Device Manager in Windows. Then, navigate
to Other Devices, find your phone, right-click,
and go to Update drivers >
Browse... > point to where you extract the USB
drivers, and Windows should do the rest.
Flash CalyxOS
Create a new folder and download the
CalyxOS release for your device
(don't unzip it though!) as well as the
device flasher
(which may be falsely flagged as a virus). From there, you
can run the
device-flasher.exe and follow along the
instructions. If you've followed the steps this far, the
only step not done is to remove the SIM card. Once you hit
enter to begin the flash, you can just sit back and wait for
it to install. Once it has, all you have to do is re-lock
the bootloader and you're set!
Next
If you need help with CalyxOS I'd recommend asking any through any of the following services:
Last, there's an blog for updates + known bugs (and fixes) that's got an RSS feed too.