https://wccftech.com/apple-watch-ecg-feature-arrives-in-china-enabled-with-watchos-8-beta-2-update/

The ECG feature in Apple Watch has been green lighted by necessary authorities in China and it is already working with the watchOS 8 beta 2 update.

Apple released the second beta of watchOS 8 yesterday. With the update, not only did Apple add polish to the software, making it more stable and usable, but enabled ECG in China for those with a compatible Apple Watch - Series 4 and up.