Replace add to cart button to an external link.

Hello,

We have a site with hundreds of products. However they can't be purchased for complex reasons (need assistance, logistics, third party payment), so we would need to add a link inside add-to-cart button and redirect to our whatsapp.

We would also would like to know if we can direct the link of the product (SKU) to Whatsapp in order to have a URL different to each product in order to receive by whatsapp exactly what client wants. 

Thank you guys

Sounds like a tricky problem, it's never going to be a great solution to have a store that you can't purchase through. The best you can probably do is to hide all of the add to cart buttons and place links in the descriptions instead. Getting the SKU is going to be harder, but you may be able to build it into the whatsapp link as the beginning of the default message (I think you can do that similar to how you populate the subject in a mailto link). Disabling the checkout process altogether is not something I know how to do.