The GrapheneOS team are unlikely to deviate from UI/UX of AOSP for features such as this, unless it can be well justified. Because the development team is small, and they're focussed on developing private and secure devices. Such a feature might be simple to implement, but a number of these features can stack up, and make maintenance of the OS much more onerous, and would likely mean that it takes a lot longer for the development team to update the OS, especially for new Android version releases. That's rather counter to the aims of the project, and therefore is avoided.