config.contentObjectExceptionHandler = 0
# Default PAGE object:
page = PAGE
page.10 = FLUIDTEMPLATE
page.10.file = fileadmin/template.html
page.10 {
  dataProcessing.10 = TYPO3\CMS\Frontend\DataProcessing\DatabaseQueryProcessor
  dataProcessing.10 {
    table = pages
    pidInList = 1
    as = subPages
    orderBy = pages.sorting
    dataProcessing.10 = TYPO3\CMS\Frontend\DataProcessing\FilesProcessor
    dataProcessing.10 {
      references.fieldName = media
    }
    dataProcessing.20 = TYPO3\CMS\Frontend\DataProcessing\DatabaseQueryProcessor
    dataProcessing.20 {
      table = tt_content
      as = inhalte
      pidInList.field = uid
    }
  }
  dataProcessing.20 = TYPO3\CMS\Frontend\DataProcessing\MenuProcessor
  dataProcessing.20 {
    #special = directory
    #special.value = <parent page uid>
    levels = 2
    as = mainMenu
    dataProcessing.10 = TYPO3\CMS\Frontend\DataProcessing\FilesProcessor
    dataProcessing.10 {
      references.fieldName = media
    }
  }
}

HTML:
<f:debug>{_all}</f:debug>
<ul>
  <f:for each="{subPages}" as="page">
    <li>
      <f:for each="{page.files}" as="file">
        <f:image image="{file}" width="320" height="280" />
      </f:for>
      <f:link.page pageUid="{page.data.uid}">{page.data.title}</f:link.page>
    </li>
  </f:for>
</ul>