Can I get Entity Cache Tags from a Route?
Adding my eventual solution based on @No Sssweat's comment.

I created a method in a service like:

public function getEntityFromRoute(RouteMatchInterface $route_match) {
  foreach ($route_match-&gt;getParameters() as $param) {
    if ($param instanceof EntityInterface) {
      return $param;
    }
  }

  return FALSE;
}


Then I have code like the following where I'm not entirely sure what entity type may be providing the route:

$route_entity = $MY_SERVICE-&gt;getEntityFromRoute(\Drupal::routeMatch());
$cache_tags = [];
if ($route_entity !== FALSE) {
  $cache_tags = $route_entity-&gt;getCacheTags();
}


Then I create my render array using the cache tags.