object.js

    {
      "data": "13/04",
      "dia": "Qui",
      "inicio": "16:24",
      "inicio_intervalo": null,
      "fim_intervalo": null,
      "fim": "20:55",
      "jornada": "05:01",
      "ocorrencia": null,
      "folga": null,
      "veiculo": null,
      "viagens": [
        {
          "saida": "00:00",
          "chegada": "00:00",
          "local_origem": "RODOVIARIA DE RIO BONITO / RBO",
          "local_destino": "RODOVIARIA DE SAQUAREMA / SAQ",
          "sentido": "ida"
        },
        {
          "saida": "00:00",
          "chegada": "00:00",
          "local_origem": "RODOVIARIA DE RIO BONITO / RBO",
          "local_destino": "RODOVIARIA DE SAQUAREMA / SAQ",
          "sentido": "volta"
        }
      ]
    }
    
    
    this.viagens = this.detalhesEscalaModal.viagens // funcionou, o indice se transformou em array, mas 
    this.viagens = Array.from(this.viagens)
    
    //isso não funcionou
    this.detalhesEscalaModal = Array.from(this.detalhesEscalaModal)

// preciso de um novo objeto com esses valores:

    let inicialized = Object.keys(this.detalhesEscalaModal).map(k => {
      return  {
            dia: k,
            inicio: k,
            inicio_intervalo: k,
            fim_intervalo: k,
            fim: k,
            jornada: k,
            ocorrencia: k,
            folga: k,
            veiculo: k }
    })

    const fields = [
      `dia`,
      `inicio`,
      `inicio_intervalo`,
      `fim_intervalo`,
      `fim`,
      `jornada`,
      `ocorrencia`,
      `folga`,
      `veiculo`
    ]

    const transformObjectUsingThis = ( fields, obj ) => ( field ) => {
      if ( fields.includes( field ) )
      return Object.assign( {}, { key: field, value: obj[ field ] } )
    }

    const arrayOfObjects = Object.keys( this.detalhesEscalaModal )
      .map( transformObjectUsingThis( fields, this.detalhesEscalaModal ) )

  	console.log('arrayOfObjects: ', arrayOfObjects)

by @suissa

  this.detalhesEscalaModal = Object.keys(this.detalhesEscalaModal)
    .reduce((acc, key) => ([...acc, { key, value: this.detalhesEscalaModal[key] }]), [])

  console.log(this.detalhesEscalaModal)

by @vinicius73

Resolvi assim, mas ainda irei refatorar p/ colocar nome nas coisas:

const obj = {
    "data": "13/04",
    "dia": "Qui",
    "inicio": "16:24",
    "inicio_intervalo": null,
    "fim_intervalo": null,
    "fim": "20:55",
    "jornada": "05:01",
    "ocorrencia": null,
    "folga": null,
    "veiculo": null,
    "viagens": [{
        "saida": "00:00",
        "chegada": "00:00",
        "local_origem": "RODOVIARIA DE RIO BONITO / RBO",
        "local_destino": "RODOVIARIA DE SAQUAREMA / SAQ",
        "sentido": "ida"
    }, {
        "saida": "00:00",
        "chegada": "00:00",
        "local_origem": "RODOVIARIA DE RIO BONITO / RBO",
        "local_destino": "RODOVIARIA DE SAQUAREMA / SAQ",
        "sentido": "volta"
    }]
}

const fields = [
  `data`,
  `dia`,
  `inicio`,
  `inicio_intervalo`,
  `fim_intervalo`,
  `fim`,
  `jornada`,
  `ocorrencia`,
  `folga`,
  `veiculo`,
  `viagens`,
  `saida`,
  `chegada`,
  `local_origem`,
  `local_destino`,
  `sentido`,
]

const transformObjectUsingThis = ( fields, obj ) => ( key ) => 
  ( fields.includes( key ) )
    ? ( obj[ key ] !== null && obj[ key ] !== undefined )
      ? ( obj[ key ].map ) 
        ? obj[ key ].map( transformObjectUsingThis( fields, obj ) )
        : Object.assign( {}, { key, value: obj[ key ] } )
      : Object.assign( {}, { key, value: obj[ key ] } )
    : ( key.constructor === Object ) 
      ? Object.keys( key )
              .map( transformObjectUsingThis( fields, key ) )
      : Object.assign( {}, { key, value: obj[ key ] } )
      
const createArrayOfObjectsUsingThis = ( fields, obj ) =>
  Object.keys( obj ).map( transformObjectUsingThis( fields, obj ) )

const arrayOfObjects = createArrayOfObjectsUsingThis( fields, obj )


console.log('arrayOfObjects: ', arrayOfObjects)

Melhor neh?

const obj = {
    "data": "13/04",
    "dia": "Qui",
    "inicio": "16:24",
    "inicio_intervalo": null,
    "fim_intervalo": null,
    "fim": "20:55",
    "jornada": "05:01",
    "ocorrencia": null,
    "folga": null,
    "veiculo": null,
    "viagens": [{
        "saida": "00:00",
        "chegada": "00:00",
        "local_origem": "RODOVIARIA DE RIO BONITO / RBO",
        "local_destino": "RODOVIARIA DE SAQUAREMA / SAQ",
        "sentido": "ida"
    }, {
        "saida": "00:00",
        "chegada": "00:00",
        "local_origem": "RODOVIARIA DE RIO BONITO / RBO",
        "local_destino": "RODOVIARIA DE SAQUAREMA / SAQ",
        "sentido": "volta"
    }]
}

const fields = [
  `data`,
  `dia`,
  `inicio`,
  `inicio_intervalo`,
  `fim_intervalo`,
  `fim`,
  `jornada`,
  `ocorrencia`,
  `folga`,
  `veiculo`,
  `viagens`,
  `saida`,
  `chegada`,
  `local_origem`,
  `local_destino`,
  `sentido`,
]

const isObject = ( something ) =>  
  something.constructor === Object

const isNullOrUndefined = ( something ) =>  
  something !== null && something !== undefined

const createObjectUsing = ( key, obj ) => 
  Object.assign( {}, { key, value: obj[ key ] } )

const ifIsArrayThenCreate = ( obj, key, fields ) => 
  ( obj[ key ].map ) 
    ? obj[ key ].map( transformObjectUsingThis( fields, obj ) )
    : createObjectUsing( key, obj )

const orIfKeyIsObjectThenCreate = ( obj, key, fields ) => 
  ( isObject( key ) ) 
      ? createArrayFrom( key ).usingThis( fields )
      : createObjectUsing( key, obj )

const ifKeyExistsInFieldsList = ( obj, key, fields ) => 
  ( isNullOrUndefined( obj[ key ] ) )
      ? ifIsArrayThenCreate( obj, key, fields )
      : createObjectUsing( key, obj )

const transformObjectUsingThis = ( fields, obj ) => ( key ) => 
  ( fields.includes( key ) )
    ? ifKeyExistsInFieldsList( obj, key, fields )
    : orIfKeyIsObjectThenCreate( obj, key, fields )

const createArrayFrom = ( something ) => ({
  usingThis: ( fields ) => 
                Object.keys( something )
                      .map( transformObjectUsingThis( fields, something ) )
})

const arrayOfObjects = createArrayFrom( obj ).usingThis( fields )

console.log('arrayOfObjects: ', arrayOfObjects)