Designed1668 GrapheneOS is always a good idea. You won't sacrifice anything in most cases, only upgrade your security.
Is Google secretly recording me in secret? Does turning off microphone and camera do anything to stop this if this is happening?
They are not doing that.
Is Google able to see what I'm doing in other apps, like websites I visit in Brave and messages I send in Signal/WhatsApp?
Well, its complicated. They might get general usage stats but not exactly what you're doing. In some cases they would be able to read your notification feed, because they are responsible for delivering them. Signal protects against this, but idk about whatsapp.
Is Google able to see what I type and what I speak despite already switching to FUTO Keyboard/Voice?
Outside of their own apps, no. Ofc inside those what you type is up to them to handle.
Can Google see my passwords stored in Bitwarden?
They could theoretically and technically do many of the things you ask, but the real question is that, are they actually doing it? They are not looking through your passwords.
Can Google see what I have in my clipboard?
Possibly. Foreground apps can always read your clipboard which displays a notification normally. Idk how Play Services interacts with the clipboard. I doubt they are reading it actively though.
Is Google listening to my conversations (both in E2EE apps and regular calls)?
Calls through other services than Google is up to those to handle. They are not wiretapping you, no.
Does Google know what files I have stored locally?
Tricky to answer. They have access to your device, and they COULD read your file tree. But again, if you don't explicitly open a file with one of their apps, its very unlikely that they collect any of your own files.
Can Google read a PDF file I have stored on my phone?
They can. But they wont.
Am I infecting my PC with Google spyware when I plug my phone into it?
No, and your PC is 1000x more likey to contain spyware.
Does Google know which apps I have installed even when I install them from outside the Play Store?
Yeah, partially because of PlayProtect. They probably still know if you disable it. FYI every app on ypur phone has access to your installed apps' names. This will be patched in Graphene eventually.
Google "spies" on people with consent mostly. Not in unexpected ways, like some chinese OEMs or Samsung does.