Note: Here is the official guide on how to install stock openpilot https://github.com/commaai/openpilot/wiki/Installing-openpilot

This installation guide will include stock openpilot as long as other forks and branches. Such as:
openpilot e2e (Branch of stock openpilot), Sunny Pilot (Fork), Shane's Fork, and Dragon Pilot (Fork), and the e2e branches for each of those forks.

Once you turn on your Comma 3 for the first time and connect it to the internet, it will display two options:

1. Dashcam mode (DO NOT SELECT THIS. This is NOT stock OpenPilot software, this is literally just dashcam mode, it will not do any driving)

2. Custom Software (This is what you want to select if you want to download stock OpenPilot (OP) Stock/E2E Long, Shane's Fork, SunnyPilot or DragonPilot (DP) )
   
   

Here are some of the fork options you can choose, these are the only ones I have tried so far:

(Type these URLs into the comma 3 “Custom Software” part)

openpilot.comma.ai

   Latest URL at the time of this post: https://smiskol.com/fork/sunnyhaibin/0.8.14-prod-c3

   Check their GitHub for the latest branch: https://github.com/sunnyhaibin/sunnypilot

   There is a nice little explanation in the middle of their GitHub on how to format the URL for the latest branch.

https://smiskol.com/fork/sshane

https://smiskol.com/fork/dp

https://installer.comma.ai/commaai/master-ci

https://smiskol.com/fork/sunnyhaibin/test-c3

Actually can't find the install URL for this one, so I have not tested it. I think it is: https://smiskol.com/fork/sshane/SA-master-e2e-long

https://smiskol.com/fork/dp/release2_e2e

These forks and features will vary heavily on what car you have. I have a 2021 Toyota Highlander, so E2E is supported. You may or may not have full functionality on your car. You can check The Official Coma Supported Vehicle Page for an idea of what Comma 3 can do for your car.

I have listed above URLs for different forks (Sunny, Shan's, Dragon), and URLs for different branches (E2E Long) for the different forks. If you find yourself needing to get different branches or forks, you can use this part below to get the installation URL for whatever branch or fork you need.

https://github.com/commaai/openpilot

https://github.com/sunnyhaibin/sunnypilot

https://github.com/sshane/openpilot

https://github.com/dragonpilot-community/dragonpilot

Go to any forks github, then you can search for specific branches:

How branch searching looks on github:

All you have to do is go on the GitHub repository for any of the software (OP, Shanes, Sunny, DP)

and find the branches:

You will take the last part of the Github URL and add it to the installer URL:

https://github.com/commaai/openpilot/tree/master-ci

https://installer.comma.ai/commaai/master-ci

https://github.com/dragonpilot-community/dragonpilot/tree/release2_e2e

https://smiskol.com/fork/dp/release2_e2e

To install a fork, you just need to type the installer URL + Fork Name:

https://smiskol.com/fork/{insert fork name}

To install the fork and branch, you will need to type the installer URL + Fork Name + Branch name:

https://smiskol.com/fork/{insert fork name}/{insert branch name}

Shane's fork custom URL example: https://smiskol.com/fork/sshane

Dragon Pilot custom URL example: https://smiskol.com/fork/dp

Shane's Fork custom URL example:

https://smiskol.com/fork/sshane/SA-master-e2e-long

Sunny Test-C3 branch custom URL example:

https://smiskol.com/fork/sunnyhaibin/test-c3

The custom fork is 'sunnyhaibin' and the custom branch is 'test-c3'

Dragon Pilot E2E custom URL example:

https://smiskol.com/fork/dp/release2_e2e

This is Dragon Pilots 'E2E' fork, their latest stable fork (That doesn't include E2E is going to be a higher release number. Keep that in mind.)

Thanks for reading, if I have made any mistakes please kindly let me know. Thanks!