This is how to assign a specific stylesheet to a specific post type post id on WordPress Gutenberg edit screen. See https://sebastien-meric.com/appliquer-gutenberg-feuille-de-style-post-id/ (in french).

add_editor_styles_by_post_id.php

<?php
/**
 * Registers a specific editor stylesheet for a specific post id.
 */
function actusoins_add_editor_styles_by_post_id() {
    global $pagenow;

    // Are we on a post edit page ?
    if ( isset( $pagenow ) && 'post.php' === $pagenow ) {
        $post_id = $_GET['post'];

        // Homepage
        if ( get_option( 'page_on_front' ) == $post_id && file_exists( get_stylesheet_directory() . '/assets/css/editor-style-home.css' ) ) {
            add_editor_style( 'assets/css/editor-style-home.css' );
        }

        // Blog homepage
        if ( get_option( 'page_for_posts' ) == $post_id && file_exists( get_stylesheet_directory() . '/assets/css/editor-style-blog.css' ) ) {
            add_editor_style( 'assets/css/editor-style-blog.css' );
        }
    }
}
add_action( 'admin_init', 'my_theme_add_editor_styles_by_post_id' );
?>