How to Ask for Details From Customer Before Adding An Item To The Cart?

[NiCaPau]

I want to to add a field that collects information for product personalisation before the customer adds the product to the cart.

There was a solution that seemed to work in 2021 but it's not working anymore: https://gist.github.com/CarsonBain/8f206795a23514916405353c0c30e3fb When I create the product.liquid template, there is no code.

Can someone please help me with this?

Thanks!