How can I customize product display based on user location?

For first-time user : A Popup will appear which will ask City ie. Mumbai or Delhi Or Pan
India.
3. Have 1 collection which has 12 products. Named Mumbai 1, Mumbai 2, Mumbai … 5,
Delhi 1, Delhi2… Delhi 5 and Pan India 1 and Pan India 2
4. If user selects Mumbai , He should get only 5 products which are tagged as Mumbai
Products. similarly for Delhi , should see 5 products. If PAN INDIA is selected, they
should see 2 products.
5. On Top Right next to Cart , Show Location Icon. Name of the location.
6. On Click of this Location, It should POP up the Location Popup window again.
7. Once he changes the city. Products should change. YOu can refresh the page.

can you brief more about logic ? currently I am on learning phase could be helpful for me