Can I create a separate admin section for my plugin?

Question

Is it against the WordPress guidelines to create a separate Administration section for my plugin? For example, Elementor opens a separate page for building pages but I'd like to create a similar administration section but do more stuff as WordPress itself does. Like items listing, editing, etc. You could say it might end up being somewhat like a whole different website inside another website I guess if I am to keep adding more features.

Please ask if more information is needed :)

Edit 1:

When an admin clicks on my plugin's admin menu, I will hide everything belonging to WordPress, like the top bar menu, sidebar, notices, etc. Or maybe I will start with a blank page and show it to only admins to avoid extra work. Would my plugin get accepted if I were to do this?

Answer 1

So, As we discussed in comments, the better approach is to do something on Frontend.

It adds unnecessary wait to the page, and therefore it isnt viable to have it on backend. If you are building plugin for your own use, then the approach of having backend filters removed on that page could be useful, but I cant recommend it for a plugin to be published in wordpress repository.

So, what you need to do is have a page on frontend, that uses a completely blank page template, and then in it do whatever you want.

So, first of all in the event for plugin activation, create a page, something like this.

When the plugin activates, you need to check if the page already exists, if it does no need to create a new page

register_activation_hook( __FILE__, 'myplugin_activate' );
    function myplugin_activate() {
    // I have set page Title as admin, because I hope thats what you would probably call it
    $new_page_title     = __('Admin','text-domain'); // Page's title
    $new_page_content   = '';               // Leave it empty, Template does the trick
    $new_page_template  = plugin_dir_path( __FILE__ ) . 'page-custom-page.php';       // The template to use for Admin Stuff
    $page_check = get_page_by_title($new_page_title);   // Why make something which exists
    // Store the above data in an array
    $new_page = array(
            'post_type'     => 'page', 
            'post_title'    => $new_page_title,
            'post_content'  => $new_page_content,
            'post_status'   => 'publish',
            'post_author'   => 1,
            'post_name'     => 'admin'
    );
    // If the page doesn't already exist, create it
    if(!isset($page_check->ID)){
        $new_page_id = wp_insert_post($new_page);
        if(!empty($new_page_template)){
            update_post_meta($new_page_id, '_wp_page_template', $new_page_template);
        }
    }
}

So we now have a page, but we need to make it empty as vacuum, because that is what you wanted.

Remember you are making a plugin, and the directory path included in answer is for plugin director, so create a file page-custom-page.php in your plugin.

Note: You wanted empty page, so there is no point of we telling you what to include in header, as you would not like to include it for your own purpose, therefore based on the info you provided template shall remain empty, and I am not showing any code for it.

One thing I would recommend is to restrict its access to non admin people, It's simple, but I still include it.

if(is_user_logged_in()){
    global $current_user;
    $Current_User = get_current_user_id();
    if(user_can( $Current_User, 'administrator' )){
        // Your Code should come somewhat here
    }
}

Now as far as admin is concerned.

Let's Again make an Admin Menu item.

function wpse_374104(){
    add_menu_page( 
        __( 'Admin', 'textdomain' ),
        'custom menu',
        'manage_options',
        'Admin',
        'Plugin_Admin_Page',
        plugins_url( 'wpse374104/images/icon.png' ),
        5
    ); 
}
add_action( 'admin_menu', 'wpse374104' );

This code is same as the last version of my answer, I just changed the Page Title.

So, now we created an arbitrary slug to which your admin menu page would link.

Now, We need a redirect.

function Plugin_Admin_Page() {

    global $pagenow;

    # Check current admin page.
    if ( $pagenow == 'Plugin_Admin_Page') {
        wp_redirect( site_url( '/admin' ) );
        exit;

    }
}

add_action('admin_init', 'Plugin_Admin_Page');

It does the trick in my opinion, I think I have answer everything needed by you, I have put a lot of effort, hope it works good for you. I am always there in comments to help further.

PSA: Incase someone else other than the person who asked question is reading this, I do not recommend putting admin stuff in frontend, as it is not a good practice, but if you do, please include link back to the admin page, or the page from the user got referred, because otherwise it becomes tough(relatively) to navigate back to admin.