Hi Steffi,
Thanks for your question. My name is Josh Wells and I am a support engineer on the Microsoft Dynamics CRM Support team.
I am not quite sure how you would strictly regulate this. The problem is due to the fact that Products have an ownership level of Organization. This means that no user or team actually owns the Product so the permissions for Product is either you have access to it (read permission set to Organization) or you don't (read permission set to none). Due to this, Products will be available for users to run Advanced Find queries on or create their own personal views that can show all Products.
The only thing you can really do is modify the filter criteria for the default view so that it returns Products where Product Manager Equals Current User.
Hope this helps. If you have any questions, please let me know.