Switched to GrapheneOS on a Pixel 8 Pro about 3 months ago. Here is my honest experience covering banking apps, camera quality, battery life, and what I miss from stock Android.
TLDR: Way more usable than I expected. Sandboxed Google Play services handle 95% of apps.
How is banking app compatibility? That is the main thing keeping me from switching.
Most banking apps work fine with sandboxed Play Services. My Chase, Fidelity, and Schwab apps all work. Some smaller credit unions might not.
The camera on GrapheneOS is surprisingly good now. They forked the Google Camera app and it takes great photos. Not quite Pixel camera quality but close.