I've originally left the Google Assistant behind, since the assistant can see and record everything on your screen. There is an alternative, Dicio, the free open-source assistant that runs locally only on your phone! It's simple, but functional too.
Now that Gemini is out, I had to give it a try! It required downloading the "Google" app, as that app is the one that actually runs your Google Assistant, get it in the Play Store. You also require the Assistant app, and the Gemini app, which may not be available in your country. In my country, Gemini was not available however I got it APKMirror. Also, while I haven't yet made any of Gemini Nano's advanced on-device features for the Pixel 8 Pro work yet, if you would like to try, you need the AICore app. Also, go into app settings for AICore, click "additional settings in app" and enable AICore Persistent.
Now, the Google app needs to be re-set as the Default Assistant App in Settings -> Apps -> Default Apps after every restart/reboot or swiping will not wake it! Gemini replaces Google Assistant as your assistant, you cannot have both assistant apps at the same time, but you can easily go into Settings in the Gemini or Google apps and switch between them quickly. The action on GrapheneOS to invoke assistant apps is to swipe from a corner of the screen inwards to the middle. I haven't been able to make "Hey Google" work, but Gemini does work on the lockscreen. Now this is your very important for your privacy; You can give or not give permissions to the Google app, and those are the permissions that will determine what Gemini can and will use, so that will determine it's capabilities. So, if you want to be able to say "call Mom" the Google app will require your Contacts and Phone privileges. Sending texts requires SMS. Using App Ops I have been able to granularity set these, allowing Send SMS but denying (ignoring actually, sends blank data to the app) Read SMS, allowing Make Phone Call, but denying Monitor Phone and Receive Phone Call. Best use for App Ops I've found. Ever! I had a very long conversation with Gemini Advanced about it's use of permissions, what data Google can get from them, and let me tell you, for a Google product, Gemini Advanced is not a fan of Google's data-grabbing practices! It gave me most excellent advice on which permissions leak the most data, and how to minimize data leakage. It really likes the App Ops approach. Call Logs can apparently be used for a lot of badness, along with Contacts... SMS is also particularly invasive.
There are 3 levels of LLM, so 3 Gemini Models. Nano is very small, for running on the Pixel 8 Pro and other flagship/future phones locally. Gemini Pro is the middle one, and Gemini Ultra powers Gemini Advanced (what comes from paying the $20 or $25 Google plan with 2TB Storage). If you just want the AI chatbot, using Gemini Pro, then that's what you get with the Gemini app. If you want Gemini Advanced, you can sign up for the 2 month free trial that should pop up as an offer if you are signed into a Google account. It should go without saying that using Gemini requires Sandboxed Play Services! Gemini Nano is for the Pixel 8 Pro. It will check your device model, and requires the AICore app to be running persistently.
Today, right before posting this I got a reminder that all of a sudden, Google turned on Gemini in Google Messages! Now, I don't know yet if it is the version that runs completely on your device and works offline, Gemini Nano, or if it is cloud based and therefore Gemini Pro or Gemini Advanced for subscribers (such as I am). I will update this once I learn more. You can use it for ideas for conversation starters, help drafting messages or quick replies. Thing like that!
Then there is the Gemini Apps Activity settling. This is where the privacy vs functionality rubber meets the road. By default, all your conversations with Gemini are saves for 18 months! They may during that time be reviewed by human annotators, after being de-anonymized, but if they are, those ones are not deleted when you choose to delete you conversations as they are kept apart from your regular conversations. Google even says, DO NOT SAY ANYTHING IDENTIFYING OR INCRIMINATING TO GEMINI! Now, you can change the Gemini Apps Activity to as low as 3 months before being auto-deleted, or you can turn it off. If off, Google will only keep your conversations around for 3 days, for quality of service or something like that, and they won't be pulled for review. The thing is, if you want Gemini to do a lot of fancy things, it has to use "Extensions." This is like setting reminders, interacting with Google Maps, and YouTube.
I have been using Gemini Advanced for about 2 weeks now. It is something that I think will actually get me, someone who hates all apps by default, and has a strict policy of never installing apps if it can be avoided, to keep the Google app on my system! With heavily reduced privileges of course.