How to implement an online store with pickup points?

Question

CMS

Good afternoon!
Which CMS to choose for the site?
Given:
There is 1 online store and 50 offline stores (pickup points). There is also free shipping over a certain amount.
Offline stores are geographically located in different cities of the region.
Prices in offline stores are different.
Required:
1. A modal window or any other form that allows the user to select a locality and a store, and then show the goods that are available there. Or definition by geo ip.
2. In the Checkout:
if the user checks "Delivery", then enters the address (if not registered);
if selects "Pickup", then the address of the store selected in point 1 is displayed.
if the user did not select anything in point 1 (by default), a list of pickup points with checkboxes is displayed - all 50 stores.
3. Once a day, update the database for each offline point.
4. Prices for the same product at different points - different (they differ in global IDs in the database - ean-13)
5. The number of unloaded goods is 5000 per point.

Answer 1

1) Do not take a ready-made CMS
2) Write the site completely by hand, configure the database and the server yourself.
3) If suddenly there are not enough skills, it is best to hire a fullstack for a project or headquarters

Answer 2

From scratch, or take some OpenCart thread as a basis and finish it off. There are multi-stores - docs.opencart.com/administration/multi-store