There are a couple of third-party store pickup apps that work with Shopify’s Locations and multi-inventory features. They allow for your locations to be shown on the cart page and may not necessarily indicate locations on the product page. I’ve handpicked a couple for you to try out:
However, I was able to find a third-party app that works with multiple locations, called Product Inventory Information. This app can show different stock levels, based on your locations, and has geolocation to help detect the nearest location for your customers. If you require assistance with these apps, you can always reach out to the developers directly through the contact information found in the Support section of the app’s page.
Let me know if this helps! If there is anything else I can help you with, let me know.