Apollo typepolicies how to read sibling field of Query?

Question

in my type policy

typepolicies:{
      Query:{
           fields:{
                getCartItems:{
                  //This is a local field
                  //I want to reference "allProducts" field here
               },
               allProducts:{
                 //Products are ferched from network and cached
               }
       }
    }
}

in my getCartItems I have a reactive var of product ids array which I want to loop over and filter out matching products with matching ids from all products field. Is there any way to reference siblings of Query fields.