I installed GrapheneOS for the first time on Wednesday last week on a used Pixel 7a, and I’m impressed. Installation was almost seamless, and I was able to do it from another Android phone. I’ve run into very few wrinkles, even using Google’s proprietary apps with GrapheneOS’s “sandboxed” version of Google Play Services. The main problems I’ve noticed: I can’t cast, and Google Timeline doesn’t seem to work (though I imagine the intersection between people keen to use GrapheneOS and keen to have Google log their location history is pretty small).