ACA_iF I'm heavily used to completely overhauling my UI (I love skeuomorphism still, I like changing the boot animation and taskbar, etc). It's just somehting I'm used go doing over the past 11 years.
Those changes can't be made in GrapheneOS as shipped. If you want to make such changes, the proper way would be to fork GrapheneOS and maintain your own builds. That way you could implement such features whilst preserving the Android security model.