generate app pass for login user

index.php

<?php

if (!is_user_logged_in() ) {
    echo "<a href='" . wp_login_url('/') . "'>login</a>";
} else {
    $user_id  = get_current_user_id(); // get user id 
    $app_name = 'app_' . date("y-m-d-H-i-s"); // create random app name
    $app_pass = WP_Application_Passwords::create_new_application_password( $user_id, array( 'name' => $app_name ) ); // generate pass
    $chunks   = str_split($app_pass[0], 4); // Split string into chunks of 4 characters
    $result   = implode(" ", $chunks); // Join chunks with space between them

    echo $result;
}