@montezh2001 The challenge you are running into is the result of an audience is if you qualified for it or not and the timestamp it qualified. It doesn't store the attribute value(s) that made it qualify at that point in time. If you want just a grouping of values for country code you may want to just use Query Service or CJA.
Both query the Data Lake, but audiences as you may have discovered are based on Profile. But in your case, a single attribute, it doesn't make any difference if the attribute is stored in one dataset.
Your SQL for QS should look something like:
SELECT countryCode, COUNT(1) from dataset group by countryCode