String comparison problem

I have this callback function in my Firmata sketch. It receives a string as a character array and does something with it. The problem is, that the string is being sent to the Arduino in T\0h\0i\0s\0 form - after each character there is a \0 terminator. As you can see, my function is switching the d13 LED on if the string incoming is COMMAND. I had tried to use several comparison methods:

• strcmp(myString, "COMMAND") == 1;
• myString == "COMMAND";
• strcmp(myString, "COMMAND\0") == 1;
• myString == "COMMAND\0";
• strcmp(myString, "C\0O\0M\0 M\0A\0N\0D\0") == 1;
• myString == "C\0O\0M\0 M\0A\0N\0D\0";
• == with saving the COMMAND to a char array variable;
• strcmp with saving the COMMAND to a char array variable;
• last two things with converting both the incoming and the needed to a String instance;
• comparing a String instance with a directly stated "COMMAND"...

Nothing works. How can I compare the strings workably?

Full Arduino sketch:

#include <Firmata.h>

void stringCallback(char *myString)
{
  if (strcmp(myString, "COMMAND") == 1) {
    digitalWrite(13, HIGH);
  }
  Firmata.sendString(myString);
}


void sysexCallback(byte command, byte argc, byte *argv)
{
  Firmata.sendSysex(command, argc, argv);
}

void setup()
{
  Firmata.setFirmwareVersion(FIRMATA_FIRMWARE_MAJOR_VERSION, FIRMATA_FIRMWARE_MINOR_VERSION);
  Firmata.attach(STRING_DATA, stringCallback);
  Firmata.attach(START_SYSEX, sysexCallback);
  Firmata.begin(57600);
  pinMode(13, INPUT);
}

void loop()
{
  while (Firmata.available()) {
    Firmata.processInput();
  }
}

Full code of the desktop program:

import pyfirmata, time

class CustomArduino(pyfirmata.Arduino):
    def __init__(self, port: str):
        pyfirmata.Arduino.__init__(self, port)
        self.iterator = pyfirmata.util.Iterator(self)
        self.iterator.start()

        self.add_cmd_handler(0x71, self.receiveString)


    def receiveString(self, *args, **kwargs):
        print(f'Raw: {args}\n'
              f'Received: {pyfirmata.util.two_byte_iter_to_str(args)}')


    def sendString(self, data):
        self.send_sysex(0x71, pyfirmata.util.str_to_two_byte_iter(data))


    def send_sysex(self, sysex_cmd, data=[]):
        """
        Sends a SysEx msg.
        :arg sysex_cmd: A sysex command byte
        : arg data: a bytearray of 7-bit bytes of arbitrary data
        """
        msg = bytearray([pyfirmata.pyfirmata.START_SYSEX, sysex_cmd])
        msg.extend(data)
        msg.append(pyfirmata.pyfirmata.END_SYSEX)
        self.sp.write(msg)


print('STRING TESTER\nPlease input your COM port: ', end = '')
myCom = str(input())
device = CustomArduino(myCom)

while True: 
    device.sendString(input('Send: '))
    time.sleep(1)

Strange detail: my Arduino is on the COM6 COM-port. If I connect it via my program and send com6 to the arduino, the D13 LED turns on!