Assuming you are monitoring your frontend application, you can use a USQL like this: "SELECT count (DISTINCT userSessionId), country FROM usersession GROUP BY country" and then create a custom metric, using the field country as dimension.
With the metric in hand, you can create a metric event whenever the country value is different from the one you need, and value is higher 1, for example.
Let me know if this helps.
Site Reliability Engineer @ Kyndryl
