Ecg app Pakistan

ECG is not currently available in Pakistan. Here is an official Apple Support link, where you can see everywhere ECG is supported --> watchOS - Feature Availability - Apple

This is as definitive as it can get as this is directly from Apple.

No. The watch will know where in the world you are.

Here is a list of countries that support the ECG app;

watchOS - Feature Availability

Pakistan is not on the list.

For the ECG app to work on your watch the ECG app has to be approved by;

A. the government of the country in which the watch was bought and

B.the government of the country in which you reside.