I've a single store for my different warehouses (currently working with a development store).
Like one store is in USA and the other one in UK. I wanted to restrict the sale for my different locations for the customers (based on location). For USA clients order should be fulfilled from USA inventory and for UK based customers, it should be fulfilled from UK inventory.
If the ordered product is low on quantity in a respected location then the order shouldn't be completed.
Is there any 3rd Party App through which I can achieve this functionality?
If the ordered product is low on quantity in a respected location then the order shouldn't be completed. If you want to restrict the sale based on location and quantity level, you could code in some logic on the product page to get the geolocation, and if the location is UK for example and the stock level is below 3 (or whatever you want to set), you could show a message that says it's out of stock, and prevent adding to the cart.
If you wanted to do it based on shipping address, you could do this in the checkout, but only if you're on Shopify Plus.
For your other challenge, of changing the fulfillment location based on shipping address and automatically fulfilling the order, our app Order Automator might be able to help. It can auto fulfill orders based on rules you select. And for the changing of location, we can make a free customization for you to achieve that. Just send me a PM or contact via our support portal speedboostr.com/contact and we can set that up for you.