drupal/core/modules/shortcut/shortcut.links.action.yml

shortcut_set_add_local_action:
  route_name: shortcut.set_add
  title: 'Add shortcut set'
  appears_on:
    - shortcut.set_admin
shortcut.link_add:
  route_name: shortcut.link_add
  title: 'Add shortcut'
  appears_on:
    - entity.shortcut_set.customize_form