app-fixed.js

import {setTransform, ReactNativeFile} from 'shared'

setTransform(file => new ReactNativeFile(file))

app.js

import {ReactNativeFile} from 'module-externe'
import {setTransform} from 'shared'

setTransform(file => new ReactNativeFile(file))

runtime-app

// false
// false

runtime-app-fixed

// true
// false

runtime-web

// false
// true

shared.js

import {ReactNativeFile} from 'module-externe'
export { ReactNativeFile } from 'module-externe'

let _transform = file => throw new Error('not implemented')
export const setTransform => transformer => _transform = transformer
export const transform = file => _transform(file)

export const process = file => {
  console.log(_transform(file) instanceof ReactNativeFile)
  console.log(_transform(file) instanceof File)
}

web.js

import {setTransform} from 'shared'

setTransform(file => new File(file))