Product quantities/locations without WooCommerce

Hi,

my WordPress 4.2.26 site is running Terso theme.
It is a catalog of products, which are not for sale, WooCommerce is not installed.
Products only have their specifications listed, now I’d like to add a button where visitors can check each product’s availability, quantity and location in real physical shops, where that specific item can actually be bought.

What is the best way to accomplish this? It does not have to be anything fancy. Is there a plugin which does that? I also think WooCommerce is not needed and it would be an overkill, because I’m not selling anything.

My clients can provide me inventory/stock data, of course. But data is changing, naturally, and visitor who clicks button must get accurate info.

Can you please let me know how this is solved properly … before I step in the wrong direction ??

Thank you so much,
lpu