code: func (pk PrivKeyLedgerSecp256k1) getPubKey() (key PubKey, err error) {
  	dev, err := getLedger()
  	if err != nil {
  		return key, fmt.Errorf("cannot connect to Ledger device - error: %v", err)
  	}
  	key, err = pubkeyLedgerSecp256k1(dev, pk.Path)
  	if err != nil {
  		return key, fmt.Errorf("please open Cosmos app on the Ledger device - error: %v", err)
  	}
  	return key, err
  }
docs: // getPubKey reads the pubkey the ledger itself
  // since this involves IO, it may return an error, which is not exposed
  // in the PubKey interface, so this function allows better error handling