Add price filter by currencies

Hello! I need to add custom price filter by currencies. I have a “Classima” WordPress theme.

The mechanism of work is as follows:

I need to add a currency filter (to existing filters by “type of ad”, “category”, “location” and “price”). There will be a checkbox field on the widget with three currencies. For example, $, ? and ?. When you click on a certain currency, the price of ads changes at the rate. The currency symbol is also changing. Currency is set manually(by formula) or (in the ideal case) it would be to take it by api)

Can this be implemented through an addition to the functions.php of my theme? Which hooks to use? Or it is a difficult task.

Thanks!