[Google Pixel 4 Guides, News, & Discussion] anupritaisno1:
If you have come across this thread you probably want a ROM that provides better security than what AOSP provides

You have 3 ROMs actually:

1) Official grapheneos (can run with locked bootloader)

2) Unofficial grapheneos (I haven't released the keys to lock the bootloader on purpose as these are highly experimental builds that test features before they land in grapheneos)

3) glassrom (these are private builds I use for myself. Not possible to lock bootloader as I build them for myself. There will be no support provided for glassrom but the stability should be pretty good and there won't be any serious bugs)

1) Installing official grapheneos

Ask for support in grapheneos IRC/official matrix. Check grapheneos.org

Important! Lately there has been a lot of spam and off topic on grapheneos IRC. Please be on topic and keep the discussion about grapheneos. Please read the grapheneos FAQ before asking questions. Starting discussions unrelated to grapheneos or spreading misinformation will definitely get you banned. Please do not do so as this wastes time of the developers.

Bugs must be reported on the os_issue_tracker on the github. Include the steps to reproduce, a log and a dmesg. Include the exact build of grapheneos as well. Reporting bugs with a modified version of grapheneos (that is, flash grapheneos and only grapheneos, nothing else) will get your report closed. See if your issue has already been opened by someone else. Do not ask for apps to be included by default on grapheneos. Read the FAQ before requesting features

If you are unsure, ask in the glassrom support group at https://t.me/glassrom and we'll redirect you to the appropriate place. That will save both your and our time. Remember to only ask about the pixel 4, for other devices you must head to the grapheneos IRC and follow the rules carefully

Follow the official installation instructions https://grapheneos.org/install

Lock your bootloader

You're done

All sources, including kernel sources are here. The build script has the exact defconfig used

https://github.com/GrapheneOS

2) unofficial grapheneos:

Ask for support in glassrom chat. https://t.me/glassrom

Kernel sources follow the same format as grapheneos and are here: https://github.com/GlassROM-devices/kernel_google_coral

Please join the telegram report or provide active feedback if you're on these builds

Go to https://github.com/GlassROM/glassrom-landing/releases

Prerelease builds are grapheneos

Download both files and verify them against glassrom-verification

Be on the latest bootloader and run:

fastboot update fastboot-image-bootable-only.zip

If you're not on the latest bootloader the bootloader is actually bundled in the update. Extract the bootable only zip and flash the boot.img to boot partition.

Use the volume buttons to select reboot recovery regardless of how you flashed it and then boot to recovery

Format data

Sideload the zip with adb sideload

Reboot

3) Glassrom

Ask for support o- you don't ask for support

Glassrom is a lineage build that provides the grapheneos patchset

Sources and flash instructions are the same as unofficial grapheneos

Use it if you miss lineage on your pixel 4 for some reason

Go to https://github.com/GlassROM/glassrom-landing/releases

All releases for pixel 4 are glassrom

Glassrom has a couple additional features:

Targeted optimization for pixel 4 CPU

An exfat driver

Forced 90 hz display

Everything you'd expect from lineageos

Fdsan is enforcing

Happy flashing