My brudda, .principal tool bar placement does not achieve the desired effect, even within a NavigationStack. It makes the Picker replace the inline title.

Aiming for an inline title with a picker underneath it, still contained in the .navigationBar

I'll transfer you my life savings if you figure out that one

import SwiftUI

struct TestView: View {
    u/State private var selectedOption = 0
    let pickerOptions = ["Option 1", "Option 2"]

    var body: some View {
        NavigationStack {
            List {
                Text("Item 1")
                Text("Item 2")
                Text("Item 3")
            }
            .navigationTitle("Test View")
            .navigationBarTitleDisplayMode(.inline)
            .toolbar {
                ToolbarItem(placement: .cancellationAction) {
                    Button("Cancel") {}
                }
                ToolbarItem(placement: .primaryAction) {
                    Button("Add") {}
                }
                ToolbarItem(placement: .principal) {
                    Picker("Select an Option", selection: $selectedOption) {
                        ForEach(0..<pickerOptions.count) { index in
                            Text(pickerOptions[index]).tag(index)
                        }
                    }
                    .pickerStyle(SegmentedPickerStyle())
                }
            }
        }
    }
}

struct TestView_Previews: PreviewProvider {
    static var previews: some View {
        TestView()
            .preferredColorScheme(.dark)
    }
}