This is Max from the Shopify Team.
Have you considered adding an additional option to your products' variants? Indicating the location as an option and then specifying the location options in conjunction with that. This way customers could see the available inventory based on location, if that's the end goal. Here's an example of this in my test store, using Debut theme:
Here are some help docs that might be of interest to you if you've not already found a solution:
If the Shopify code doesn't allow for this data to be transmitted to the front end, how could a Shopify expert help solve this issue? According to https://community.shopify.com/c/Technical-Q-A/Locations-Display-Inventory-by-Location-on-Front-End-T... the data is not passed through to the front end.
I also have this problem and need to find a solution. It should be seen as a big priority for Shopify as many retailers have multi locations and need to display inventory by store to the customer.
This sounds like a very useful feature!
I would rather like to implement it in the app itself, so other users can use this feature too. (and otherwise tech savvy competition would be able to figure out how to get to the numbers, so it's better to make sure no number appear in the ajax request).
For now you could use the in stock / out of stock setting to hide the numbers.
I will add this new feature tomorrow, then you will be able to add your treshold quantities for out of stock / low stock / high stock message.