ASP.NET Core Custom Policy Based Authorization - unclear

OK, Custom Policy Based Authorization in ASP.NET Core. I kinda of understood the idea of this new identity framework, but still not 100% clear what you can achieve with this. Assuming we have an Action in HomeController called List. This action will query and display a list of products from the database. The users that must access this list must be part of the Marketing division. Therefore in our policy we check if user has a claim called Division and the value of that is Marketing. If yes then he will be allowed to see the list otherwise not. We can decorate our action like this:

[Authorize(Policy = "ProductsAccess")]
public IActionResult List()  
{
    //do query and return the products view model
    return View();
}

All good with this. It will work perfectly.

Scenario 1: What if I want to add the policy at the product level, and based on the policy the user will see only the products from his division. So marketing guy will see his products, R&D will see his and so forth. How can I achieve that? Can it be done with a policy? If yes how?

Scenario 2: What about access at the field level? Let's say maybe I want to hide certain fields? Example: all products will have certain columns that must be visible to Managers and hidden to the rest of users? Can this be done using custom policies? If yes how?