WP How to selectively display posts based on city?

Question

Geolocation

I want records to be shown on the main page of sparado.ru first from the city where the visitor is located, and then all the rest.
And so that there is a widget on the side, where the visitor can specify the city.
I understand that there are paid plugins, but the budget is limited. You need a free one, or somehow modify the demo version of the paid one.