I don’t think this is easily possible because pickle is a binary format, so you have to load the file as a whole as far as I know. The easiest way to accomplish that is to use the exam same functions and classes you defined in the script that you used to generate the pickle file and then try to load it. Once you have loaded the model, you can then access the dict via model.state_dict().
(Also, like vahid suggested, are you sure that this is a regular pickle file and not one created via pytorch?)
Also note that you need to use the exact same PyTorch version etc.