The function actually works.
The new series 4 for Singapore will not do ECG. That's the only function I want in the new watch.
For USA users, it's just additional graph that shows your heartbeat and other data.
The current model (latest update on the watch and your phone), works and I have tried it myself. Just google and you will see various results from other parts of the world already using it since it was updated in December.
The ECG function reads every second or they called it "streaming beat / ECG". When you first touch the crown with your index finger, it will start with ECG. Then it will stream until you stop touching the crown.
When you do not touch the crown, it's either "Sedentary or background".
Where can you view it?
Go to your phone -> Open Health -> Click on your Apple Watch you name -> scroll down and you will see "Heart Rate" -> From there all the info is inside -> Look for "Heart Rate Context" and you will know if your ECG is working. If will say ECG (it might show streaming beat at first but once it's updated, it will show ECG).
Plus any reason why you want ECG? Please remember, your Apple Watch is only an indicator and might not be 100% accurate. If you need to read your actual ECG, it best to go see your doctor.
I am sure sooner or later the ECG function will be able to use in other parts of the world, including Singapore.