I know I'll be missing the camera quality and easy to access photos.
I'm not sure if you're really missing out on anything in this regard. If you use the Pixel Camera app already mentioned by Dumdum, you'll get the same image results as with stock Google Pixel. Depending on which iPhone you used, your Pixel 9 Pro XL's image results are probably at least as good if not better.
https://www.dxomark.com/smartphones/
Also does it save to grapheneOS's stock photo app or is there something else to download?
You'll also be pleasantly surprised when it comes to ease of access. The standard GrapheneOS Gallery app is solid but there are better, more feature rich options you can install for viewing and editing photos.
Here are a few subjective recommendations that come to mind:
Aves Gallery
Lacoblonut Gallery
ImageToolbox
Not tested myself, but often recommended in the forum here:
Fossify Gallery
If you're looking for an iCloud Photos-like experience, Ente might also be something for you.
All apps mentioned are available on Google Play Store (if you're just switching over, this may be the easiest way to get started with GrapheneOS) as well as on Github and F-Droid.
Of course, you could also just install and use the Google Photos app.