How can I modify a dynamic buy button to redirect to a new checkout page?

hi I need to change

{ form | payment_button }}

this dynamic buy button in my product.liquid to redirect to the checkout as usual but with this added to the link “/checkout?force_checkout=redesign”, so the checkout is the new one-page checkout. I manage to change it in the cart using

but can’t do it on the dynamic button in the product page

I could add a custom button:

{%- render 'icon' with 'lock' -%}

{{- ‘cart.general.checkout’ | t -}}

but this would not add the item to the cart so it is an empty checkout