Latest Prestashop PayPal module is not visible for "visitors" until they enter address and press save on OPC page.
It is automaticaly visible for registered or loged customers, but for visitors is not visible on OPC, they first need to enter address and press save, and PayPal will instantly become a visible as payment options (of course if you configure PayPal as active payment solution).
So you can use PayPal on any OPC module, (but PayPal as payment option will not be visible until they enter address & save, or until they login)