const dados = [
    { id: 1, nome: "Primeiro envio",
      estatistica: [
        { id: 1, entregues: 0 },
        { id: 2, entregues: 2 }
      ]
    },
    { id: 2, nome: "Segundo envio",
      estatistica: [
        { id: 1, entregues: 1 },
        { id: 2, entregues: 3 }
      ]
    }
];
 
// for of
let soma = 0;
for (const dado of dados) {
    for (const item of dado.estatistica) {
        soma += item.entregues;
    }
}
console.log(soma);
 
// for tradicional
soma = 0;
for (let i = 0; i < dados.length; i++) {
    for (let j = 0; j < dados[i].estatistica.length; j++) {
        soma += dados[i].estatistica[j].entregues;
    }
}
console.log(soma);
 
// reduce, olha a zona
soma = dados.reduce((x, y) => x + y.estatistica.reduce((a, b) => a + b.entregues, 0), 0);
console.log(soma);
 

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