Started a rewrite of my app using the newest SwiftUI and Xcode (Version 14.0 beta 2 (14A5229c))

Out of the box, it appears Settings is not compatible with DocumentGroup. At least I can't get it to work.

Any examples?

You mean on iOS? There Settings is not available. But on macOS I didn't find any problem. Do you test on macOS Ventura?

The app below does work for me in Xcode 14 beta 2 and macOS Monterey.

import SwiftUI
import UniformTypeIdentifiers

@main
struct MyApp: App {
    var body: some Scene {
        DocumentGroup(newDocument: MyDocument()) { configuration in
            ContentView(document: configuration.$document)
        }

        #if os(macOS)
        Settings {
            GeneralSettings()
        }
        #endif
    }
}

struct GeneralSettings: View {
    var body: some View {
        VStack {
            Text("Hello world")
                .padding()
        }
        .padding()
        .fixedSize()
    }
}

struct ContentView: View {
    @Binding var document: MyDocument
    @Environment(\.undoManager) var undoManager

    var body: some View {
        TextEditor(text: $document.text)
            .toolbar {
                ToolbarItemGroup(placement: .automatic) {
                    if let undoManager = undoManager {
                        Button(action: undoManager.undo) {
                            Label("Undo", systemImage: "arrow.uturn.backward")
                        }
                        .disabled(!undoManager.canUndo)

                        Button(action: undoManager.redo) {
                            Label("Redo", systemImage: "arrow.uturn.forward")
                        }
                        .disabled(!undoManager.canRedo)
                    }
                }
            }
    }
}

struct MyDocument: FileDocument {
    var text: String

    init(text: String = "Hello, world!") {
        print("⚫️ ", #function)
        self.text = text
    }

    static var readableContentTypes: [UTType] { [.plainText] }

    init(configuration: ReadConfiguration) throws {
        guard let data = configuration.file.regularFileContents,
              let string = String(data: data, encoding: .utf8)
        else {
            throw CocoaError(.fileReadCorruptFile)
        }
        print("⚫️ ", #function)
        text = string
    }

    func fileWrapper(configuration: WriteConfiguration) throws -> FileWrapper {
        let data = text.data(using: .utf8)!
        return .init(regularFileWithContents: data)
    }
}