Clone WP plugins to Core PHP

I’m migrating an existing WordPress-based store to a completely independent Core PHP application. My goal is to replicate, one-for-one, the best parts of several WP plugins without relying on WordPress at all.

Here is what I need reproduced and working seamlessly in clean, well-documented PHP:
I’ll provide the current database schema and front-end HTML/CSS. You return:

1. Google Site Kit
2. Broken Links Checker
3. SEO/Social Management tools (post, shop)


1. Core PHP code (namespace-organised, PSR-12 compliant).
2. SQL for the new tables.
3. A concise setup guide so my server team can deploy without WordPress present.
4. NO 3rd party vendors! Only API source companies!

Please provide estimated timeframes and costs for "Google Site Kit" as a start.
Clean architecture, security best practices, and easy extensibility will decide the winner IF doable.

Need ALL features in the plugin! Goes to the eCommerce Core PHP custom platform