I'd love to see a pie chart as well, which can be used in Lock Screen circular widget. However, this doesn't seem possible just yet.

You need to first use Xcode 14 beta, then embed the Swift Charts (which is SwiftUI view) to your code using one of the bridging tools below https://developer.apple.com/documentation/swiftui/swiftui-views-displayed-by-other-ui-frameworks

Thanks for confirmation. So basically I have to subclass UIView and implements UITextInput to start with? On Mac, this may mean subclassing NSView and implements NSTextInput / NSTextInputClient?