GrapheneOS used MTE long before Google made a very limited form of it available as an opt-in feature via Android Advanced Protection Mode. Pixel 11 shipped without support for MTE available to the OS and still doesn't have that with the production firmware. It's only available with the Android 17 QPR2 firmware. It needs to have hardware and firmware support for it for GrapheneOS to use it. We also need to know it's fully functional.