Pop-up stores or restaurants are types of events. As you probably know, events are only to be mapped on Google Maps if they occur repeatedly at the same time (regularly). This does not take away your question: should there be a solution to promote and inform people about Pop-Up shops. Personally, I think it is a trendy popular thing right now, that merits someone to blog about it and create a Google MyMaps with a link to the store location and the related blog post with info about each pop-up store.
If you are highly motivated for this to happen, I would look for a publishing company that makes cultural event listings for Paris and see if they are interested in running away with your idea. Don't forget to sell them the idea to use Google Maps (MyMaps) to help people navigate to stores with their phones ;-) We are ambassadors of Google Maps after all.