Four simple scripts:

1. Enumerate all WP posts by their ID and get canonical links.
2. Get all authors from Wordpress REST API
3. Guess plugins from REST API endpoints and scan for available post types
4. Extract info from single post or page, check Internet Archive for archival records

php spy.php
php spy-users.php
php spy-api.php
php spy-post.php

or

php spy.php some_wp_site.com

You can skip RSS analysis step by providing start and end post ID to scrap:

php spy.php some_wp_site.com 1 12345