How do you render a Node's Last Saved date in a Region Footer (ie, inside a Block on every page)?
I think you can add to the yourtheme.theme file next thinks;

function yourtheme_preprocess_region(&amp;$vars) {
  $vars['node'] = \Drupal::routeMatch()-&gt;getParameter('node');
}


and afterwards in your twig template each region will have available variable node. 

{% if node %}
  {{ node.changed.value|date("d/m/Y H:i") }}
{% endif %}


Don't forget to clear cache.