GrapheneOS has the same camera features and quality as the stock Pixel OS within the same apps. You can use Pixel Camera on GrapheneOS even without sandboxed Google Play in the same profile if you want the full feature set. If you want extremely good cameras, the Pixel 10 Pro and Pixel 10 Pro XL are the best choices. Those provide the highest quality image sensors among the available supported devices and the Pro mode in Pixel Camera. See https://www.dxomark.com/smartphones/ for how those compare to other devices. Our own Camera app will be heavily overhauled to narrow the gap more with the Pixel Camera app but you can already use that especially if you care a lot about this.

You can run the proprietary Pixel camera software on GrapheneOS just fine (properly sandboxed).

GrapheneOS only works on Pixel devices so it only targets a very limited set of Android camera hardware.