Unfortunately, as far as I can tell, this only makes Shopify display a pickup location if an item is in stock there, but it doesn't specifically say that that item is NOT in stock at the "empty" location. So, the lack of that store as an option looks like a bug to end user: "How come I can't pick Store X?"
I see it is an old question but I would like to add a reply to this for the people who are coming to the topic from Google.
We recently created a Shopify App which is doing that.
This app allows you to display per location inventory on product pages. Also you can display your opereation hours with that.
We have a free plan take a look into it.
I see that our inventory information app https://apps.shopify.com/product-inventory-information has sparked your interest to create a copy of it's functionality. It's somewhat unfortunate that after I listed my app on a certain website at the end of september 2 developers decided to copy it (one app published in december, the other one in January.) But I guess that's what you get when your app get's attention.
anyway, I like the layout of the popover in your app and great idea to have the opening times available there as well, we currently only show it on our google map featur, we might just copy that idea
It's not a very big niche, so I hope we can all get some happy customers, good luck!