Starting this summer (Northern Hemisphere?), Samsung will add Irregular Heart Rhythm Notification (IHRN) to its Samsung Health app in 13 markets. The list of countries includes Argentina, Azerbaijan, Costa Rica, Dominican Republic, Ecuador, Georgia, Guatemala, Hong Kong, Indonesia, Panama, UAE, Korea, and the US.
It will work in the background by analysing your heart rate, and when it detects signs of AFib, you will be notified to record an ECG.
Yes, this is really way after Apple, and the use of the temperature sensor was also a good year after the sensor appeared on the watches. Samsung does seem to be lagging rather badly on the watch side (despite it being claimed to be one of the best Wear OS watches around).
See https://www.androidpolice.com/samsung-galaxy-watch-irregular-heartbeat-save-your-life/