I have a Pixel 6 Pro. Different phone, but same generation and same SoC so the experience should probably large be the same. I had zero problems installing GrapheneOS. The web installer was much easier to use than recoveries like TWRP. Performance is really good, fast and smooth. Can't tell the difference between GOS and stock. Hope that answers your questions.
Yes. A Pixel Tablet was released recently. GrapheneOS (a good privacy-focused custom ROM) supports it too. And iirc the tablet supports USI2.0 stylus. But it's 500$ US brand new