Adding shop picker to custom menu and listing all shops

Hi, so here is the next issue I'm trying to solve .I am running a multisite with grid market and I want to add the shop picker to my custom menu. I know that shop picker is in the default side bar but I have replaced that with my own custom menu sidebar but still need the shop picker, however I am not seeing that as an option to add in the custom menu area.
Also I have a separate page dedicated to listing all shops but I do not see a way to do that. I know that there is short code to list all products is there a way to do something similar but with shops.
Thank you
Meriam