JSFiddle - React, Tailwind, and code Playground

JavaScript

const raw = [{
  date: '2018-8-1',
  devices: [{
    id: 1,
    name: 'iphone',
    device_age: 12
  }, {
    id: 2,
    name: 'samsung',
    device_age: 10
  }]
}, {
  date: '2018-8-2',
  devices: [{
    id: 1,
    name: 'iphone',
    device_age: 5
  }, {
    id: 2,
    name: 'samsung',
    device_age: 9
  }]
}]

let result = raw.map((obj, i) => {
   return {
       date: obj.date,
       [obj.devices.map(innerObj => innerObj.name)]: 'test'
   }
})
console.log(result)
//expectd [{date: '2018-8-1', iphone: 12, samsung: 10}, {date: '2018-8-2', iphone:5, samsung:9}]