How to modify the page at admin/structure/types? Using Drupal 8, I'm trying to modify the page at "/admin/structure/types" .This page is not a form (instead it is an entity list), so it cannot be modified with hook_form_alter.

_entity_list: The value is entity_type. Provides a list of entities using the EntityListController of the respective entity. E.g. _entity_list: view_mode returns the render array of a list of view modes.

Which hook can I use to modify an entity list ?

I have tried 


mymodule_structure_types_prepare_form 
mymodule_structure_prepare_form


and none of those is triggered.
see Can you change the list builder class used by an entity?

Using hook_entity_type_alter() you can override the list builder for nodes.

You can add a custom NodeListBuilder in your module that extends or replaces /core/modules/node/src/NodeListBuilder.php

This class is pretty simple, so it should be easy to add or remove rows to the table displayed.