On iOS it's not too difficult to build a fully custom UI with just UIKit. You want a totally custom button? No problem, don't fight the styling inherent with UIButton, just subclass its parent class UIControl instead which is a blank canvas, but still gets you 90% of the perks of a standard UIButton with minimal effort. It's pretty easy to write entirely custom widgets with unique behaviors too.
It's a bit more messy to do that with Android Framework, and because of that I see more of an argument for using Flutter there than on iOS. Jetpack Compose seems to be a lot better in that regard though.
It's a bit more messy to do that with Android Framework, and because of that I see more of an argument for using Flutter there than on iOS. Jetpack Compose seems to be a lot better in that regard though.