I'm planning on getting P7 and flashing GrapheneOS. What I want to know is what features does GOS keep from the Pixel stock ROM. Like voice commands, photoshop eraser, photo unblur and other features. If they aren't included in GOS is there a way to get them while keeping the privacy?
GrapheneOS features
You really need to read this and FAQ:
https://grapheneos.org/usage
Install Google Play and Google Photos for the photo editing stuff. It works the same on GOS.
I got Google Assistant working on my phone but it needed internet access. OK Google from the lock screen might not work, but otherwise most of the features you're looking for work on GOS by installing the correct apps.