ECG

According to this

https://www.apple.com/watchos/feature-availability/#branded-ecg

ECG works in the Ukraine .

Did you purchase your Apple Watch in the Ukraine? If not, then it is most likely a case of the country where you purchased the Apple Watch having not approved ECG yet.

That I do not know. Has the iPhone region been changed to the Ukraine

https://support.apple.com/en-us/HT201389

NOTE: I DO NOT know if that will affect anything, but it is worth a try.

After that, I suggest contacting Apple Support

Get Support