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 my_theme_add_editor_styles_by_post_id() {
    global $post, $pagenow;

    // Homepage
    if ( isset( $pagenow )
            && 'post.php' === $pagenow
            && get_option( 'page_on_front' ) == $post->ID
            && file_exists( get_stylesheet_directory() . '/editor-style-home.css' )
    ) {
        add_editor_style( get_stylesheet_directory_uri() . '/editor-style-home.css' );
    }

    // Blog homepage
    if ( isset( $pagenow )
            && 'post.php' === $pagenow
            && get_option( 'page_for_posts' ) == $post->ID
            && file_exists( get_stylesheet_directory() . '/editor-style-blog.css' )
    ) {
        add_editor_style( get_stylesheet_directory_uri() . '/editor-style-blog.css' );
    }
}
add_action( 'pre_get_posts', 'my_theme_add_editor_styles_by_post_id' );
?>