I took a look through the apps that we have available on our platform, but I don't think there's anything that would work for this specifically.
However, I have a couple of workarounds that I think could be relevant. If that's what you're wanting you could have iPads or computers around your store for your customers to use and then you could just have your website up for them to browse. This would allow them to search your store to see what you have available.
The other option would be to get a catalog app like Panda Catalogue. It won't allow you to show your item inventory, but you can make a PDF catalog to showcase all of your products for your customers to browse. If you're wanting them to search, however, I suggest you just have your website available to them so that it's a more "live" experience.
Does that help to answer your question?
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