Can't derive xpub

[cedvdb]

When deriving an xpub I have the error Missing private key for hardened child key. Aren't you supposed to be able to derive with only the public key, for watch only wallets for example ?

import 'package:bip32/bip32.dart' as bip32;

void main(List<String> arguments) {
  final base58 = 'xpub661MyMwAqRbcFxtSX21UXfaDwmdN5zmJ1C8t1cjviNkkW6gXCd7AcfciXRuhPerjhnpziEXb2fsWkAVsNEJhgM5BPgnenuDDXVPbJSadrUG';
  final node = bip32.BIP32.fromBase58(base58);
  final derived = node.derivePath("m/44'/0'/0'/0/0");
  }