How do I activate a certain block template only when editing the front page?

Setting $post_type_object->template seems to be done on ‘init’ (or close to it) while is_front_page() is set later, so I had to use $_GET['post'] instead. I also changed get_post_type_object( 'post' ) to ‘page’. Like this:

add_action( 'init', 'home_block_template' );
function home_block_template() {
    if ( ! is_admin() || ! isset( $_GET['post'] ) || get_option( 'page_on_front' ) !== $_GET['post'] ) {
        return false;
    }

    $post_type_object = get_post_type_object( 'page' );
    $post_type_object->template = array(
        array( 'core/list' ),
    );
}