Hi Stefano,
you can use a Form component to add in the P2 page with an hidden field to preload the ID value. In this way, you model a flow by the form to the P1 page passing the ID value, without use the list.
When you pass the ID value from the P1 page to the P2 page you need to model a normal navigation flow by the L1 list to the L2 list and a data flow from the L1 list to the form component to pass the ID to the hidden field.
Best regards
Ombretta