Can I add CSS to a YAML generated page ? (Sorry if that's Drupal 101, but I'm still at the very bottom of the learning curve ..)

I have a custom module, with a routing file that redirects to a path that I have chosen arbitrarily : 

grefsearch:
  path: 'solr-search/content'
  defaults:
    _controller: '\Drupal\gref\Controller\GrefSearchController::search'
  requirements:
    _permission: 'use gref search'


I have another YAML config which describes the View that must be rendered when accessing to solr-search/content :

langcode: en
status: true
dependencies:
...
page_1:
    display_plugin: page
    id: page_1
    display_title: Page
    position: 1
    display_options:
      display_extenders: {  }
      path: solr-search/content
      cache:
        type: none
      defaults:
        cache: false
    cache_metadata:
      contexts:
        - 'languages:language_content'
        - 'languages:language_interface'
        - url
        - url.query_args
      cacheable: false
      max-age: -1
      tags:
        - 'config:field.storage.node.body'


Since the page is completely YAML-based, I do not have a Twig template that is linked to it, and because of that, I cannot use hooks like template_preprocess_page because I cannot name the function properly. 

I'm a bit lost. Should I change the structure I have, and render the page in a Twig template anyway ?
Thanks !
You can still use the hook_preprocess_page for a specific path like this:

/**
 * Implements hook_preprocess_HOOK().
 * Implements hook_preprocess_page().
 *
 * @param $variables
 */
function mymodule_preprocess_page(&amp;$variables) {
  $current_path = \Drupal::service('path.current')-&gt;getPath();
  if ($current_path === '/solr-search/content') {
    $variables['#attached']['library'][] = 'my_module/my-css-library';
  }
}