Code to Update Prices and add them for Woocommerce Custom Product Variations Loop

I am actually struggling with some custom functions. Actually My aim is the following:
Create 2 custom fields in a woocommerce variable product backend ✔
Show these custom fields text and prices in frontend
Make able to add the product in the cart with these prices summed up.

I don’t know which hook I am using wrong and why the theme ajax doesn’t work.
There is someone that can assist?

“Working” (I hope) Code

Code Struggle:

Other non functional code:

Thank you!