Dynamic Island Progress Demo in SwiftUI. Demo here: https://twitter.com/ericlewis/status/1656283504747880451

ContentView.swift

import SwiftUI

let size: CGSize = {
    return .init(width: 126.0, height: 36.9)
}()

let origin: CGPoint = {
    return .init(x: UIScreen.main.bounds.midX - 0.3, y: 29.4)
}()

struct DynamicIslandProgressViewStyle: ProgressViewStyle {
    func makeBody(configuration: Configuration) -> some View {
        Capsule(style: .continuous)
            .fill(.black)
            .frame(width: size.width, height: size.height)
            .overlay {
                Capsule(style: .continuous)
                    .trim(from: 0, to: configuration.fractionCompleted ?? 0)
                    .stroke(
                        style:
                            StrokeStyle(
                                lineWidth: 5,
                                lineCap: .round,
                                lineJoin: .round
                            )
                    )
                    .rotation3DEffect(
                        .degrees(180), axis: (x: 0, y: 0, z: 1))
            }
            .position(origin)
            .edgesIgnoringSafeArea(.top)
    }
}

struct DynamicIslandProgressViewModifier<Value: BinaryFloatingPoint, Style: ShapeStyle>:
    ViewModifier
{
    let value: Value
    let total: Value
    let style: Style
    
    func body(content: Content) -> some View {
        ZStack {
            ProgressView(value: value, total: total)
                .progressViewStyle(DynamicIslandProgressViewStyle())
                .foregroundStyle(style)
            content
        }
    }
}

extension View {
    func dynamicIslandProgress<Value: BinaryFloatingPoint, Style: ShapeStyle>(
        value: Value, total: Value = 1.0, style: Style = .tint
    ) -> some View {
        self.overlay {
            Color.clear.modifier(
                DynamicIslandProgressViewModifier(
                    value: value,
                    total: total,
                    style: style
                )
            )
            .edgesIgnoringSafeArea(.top)
        }
    }
}

struct ContentView: View {
    
    @State
    private var progress = 0.0
    
    let total = 49.0

    var body: some View {
        NavigationView {
            List {
                Stepper("Progress", value: $progress.animation(), in: 0...total)
            }
            .navigationTitle("Dynamic Island thingie.")
            .navigationBarTitleDisplayMode(.inline)
        }
        .dynamicIslandProgress(
            value: progress,
            total: total,
            style: .linearGradient(
                colors: [.red, .green, .blue],
                startPoint: .bottomTrailing, endPoint: .topLeading)
        )
    }
}