#include <vector>

std::vector<std::array<byte, 4>> lista = {{ {1,2,3,4}, {5,6,7,8} }};


void setup()
{
  Serial.begin(9600);

  PrintLista();
  
  Serial.println(lista[1][3]);
  
  Serial.println(lista[2][3]); // pegando próximos bytes indefinidos

  lista.push_back({9,10,11,12});

  Serial.println(lista[2][3]);

  Serial.println(lista.size());

  lista.push_back({11,22,33,44});

  PrintLista();
}

  void loop(){delay(9999);}
  void PrintLista()
  {
    Serial.println("{");

    for (byte i = 0; i < lista.size(); i++)
    {
      Serial.print("  {");
      
      for (byte j = 0; j < 4; j++)
      {
        Serial.print(String(lista[i][j]) + ",");
      }

      Serial.println("},");
    }

    Serial.println("}");
  }