location filter on our ecommerce website both our website and flutter app and deep link

our eCommerce website operates in several cities in the country. we have sellers in different cities and We would like to included a location filter on the home page , category page, search page as well which gives the user the ability to filter the location to his city and all sellers of his cities products are shown to him.
to do this
1. Admin would create the locations in the back end. Country, state, city . Admin can add as many countries, states and cities as he wants .

2. sellers select the location on the registration page and also can change it on the the sellers edit profile page

3. the location based filter appears on the home page and also in the products columns toe alert users that the product is based in this city .

4, when a customer change the city to a specific city, it refreshes the pages and all the products from sellers in the particular city are shown to the customer.

5. the product page should contain a label or alert notifying the user that the product is based in the city .

6. the store front of the seller should also contain the sellers location

7. all products grid view, home page, search page, category page and sellers store front page should have that alerts, example. location of this product is in (city’s name )

8. the check out page, favorite product pages and wish list page should also indicate the alerts, example. location of this product is in (city’s name )

9. there is no deep link for app, deep link should be included

10. force users to update the app when there is a new app uploaded in the play store or app store