Currently, EPOPOOS is selling a comparatively well-equipped smartwatch, not least because of its AMOLED display. The device supposedly supports Bluetooth 5.0, up to 20 days of battery life and heart rate tracking, too.
https://www.notebookcheck.net/EPOPOOS-launches-a-smartwatch-with-an-AMOLED-display-IP67-certification-and-local-music-playback-support-for-US-59-99.550236.0.html