playing around with published sequence types, you need wrapper objects

ArrayOfArrayView.swift

//
//  ArrayOfArrayView.swift
//  PublishedList
//
//  Created by Paul Wood on 8/23/19.
//  Copyright © 2019 Paul Wood. All rights reserved.
//

import SwiftUI
import Combine

struct IntItem: Identifiable, ExpressibleByIntegerLiteral {
  var value: Int
  var id: Int { return value }
  init(integerLiteral value: Int) {
    self.value = value
  }
  init(_ value: Int) {
    self.value = value
  }
}

struct ArrayHolder<U: Identifiable>: ExpressibleByArrayLiteral, Identifiable {
  typealias ArrayLiteralElement = U
  
  var array: [U]
  var id: UUID = UUID()
  
  init(arrayLiteral elements: U...) {
    self.array = elements
  }
  
  init(_ array: [U]) {
    self.array = array
  }
}

class DataSource: ObservableObject {
  @Published var arrayHolder: [ArrayHolder<IntItem>] = [[0],[0,1]]
  func plus() {
    if arrayHolder.count < 5 {
      if arrayHolder.count > 0 {
        let currentArray = arrayHolder[arrayHolder.count - 1]
        let nextToAdd = IntItem(currentArray.array.last!.value + 1)
        let nextArray = currentArray.array + [nextToAdd]
        let nextHolder = ArrayHolder(nextArray)
        arrayHolder.append(nextHolder)
      } else {
        arrayHolder.append(ArrayHolder<IntItem>([0]))
      }
    }
  }
  func minus() {
    if arrayHolder.count > 0 {
      arrayHolder.remove(at: arrayHolder.count - 1)
    }
  }
}

struct ArrayOfArrayView: View {
  @ObservedObject var ds: DataSource = DataSource()
  var body: some View {
    VStack{
      Spacer()
      HStack(alignment: .firstTextBaseline) {
        Text("List of Items").font(.title)
        Text("Maximum of 5").font(.subheadline)
      }
      VStack{
        ForEach(ds.arrayHolder){ (item: ArrayHolder) in
          HStack {
            ForEach(item.array) { (i: IntItem) in
              Text("\(i.value)").font(.headline)
            }
          }
        }
      }
      HStack{
        Spacer()
        Button(action: ds.plus) {
          Image(systemName: "plus")
          .font(.title)
          .padding()
          .background(
            Circle().foregroundColor(Color.accentColor.opacity(0.3))
          )
        }
        Spacer()
        Button(action: ds.minus) {
          Image(systemName: "minus")
          .font(.title)
          .padding()
          .background(
            Circle().foregroundColor(Color.accentColor.opacity(0.3))
          )
        }
        Spacer()
      }
      Spacer()
    }.animation(.default)
  }
}

struct ContentView_Previews: PreviewProvider {
  static var previews: some View {
    ArrayOfArrayView()
  }
}

something like [[Int]] where int is Identifiable via extension doesn't create a good sample code.

In short you should prefer to use structs/classes to abstract the data that is displayed to a user even in a tutorial. You can use ExpressibleByIntegerLiteral or ExpressibleByArrayLiteral to shorten your code to something newcomers to the language can understand. This also prevents issues with operator overloading for example Array.append doesn't always do what you expect.