Virtually every issue I have with GrapheneOS stems directly from the lack of Google Play Integrity causing app incompatibilities. There's some little bits of friction here and there like security mitigations causing app crashes, but when that happens the OS tells you exactly what happened, why, and how to prevent it in the future (there's toggles to disable specific mitigations on a per-app basis). If the OS was deployed widely, those crashes would likely disappear as patches get deployed by developers.
It's very polished and completely usable as a daily driver.