Magento 2 - Custom Options adjustments

I need a Magento BE developer that can provide a simple module for add to cart events.

We are not creating any custom option for products but need to add custom options to any product that have a specific custom attribute set to YES, while adding to cart with rest api.

We have a considerable catalog and for a new ERP integration, we need pass on specific data in the custom_options API section ( extending the API to achieve the result below would also be acceptable)

we do NOT want to create custom options on every product or save them in database against them, but more like trick Magento in saving something as custom options in order items ( and API)

General considerations :
- we have an attribute "calculator_enable" type boolean - which controls if a product is a square meter type product / we only require these custom options to be saved agains products that are set to YES
- we have an attribute "box_content" that is a numeric figure and holds the amount of square meters in a box


What we need to add
- "Qty per box " : value of the box_content product attribute
- "M2 ordered" : calculation between order item qty and Qty per box ( as a 2 decimal number)