Currently, when searching for geographic locations with our native Search Box element, you're able to set the radius for which you would prefer your results to be within.
This field will become available after setting up a dynamic expression for the "Prefer results around" field of the Search box element. Though this does not limit the results to only within a specific country, it can server as a good alternative. We'd recommend trying this out as it may help you to further confine your results.
