Other people have noted that you can switch out the keyboard and SMS app (which I did).
My single (minor) issue with GrapheneOS is the adaptive screen brightness. On the stock Android OS on a Pixel I'd mess around with the sliders for a week or two on a new phone and then it learned what I liked. Now it has a few set values, one of which is always too dim for me in darker conditions so I have to mess with the slider each and every time. I don't believe there's a way of fixing that.
Other than that I'm glad I switched, especially when I read about new "features" they add that I know I'd hate.
My single (minor) issue with GrapheneOS is the adaptive screen brightness. On the stock Android OS on a Pixel I'd mess around with the sliders for a week or two on a new phone and then it learned what I liked. Now it has a few set values, one of which is always too dim for me in darker conditions so I have to mess with the slider each and every time. I don't believe there's a way of fixing that.
Other than that I'm glad I switched, especially when I read about new "features" they add that I know I'd hate.