KESHUYOU is selling the GT5 smartwatch globally via AliExpress. The smartwatch is reported to have heart rate, blood pressure and blood oxygen level sensors, though their accuracy is unproven. Plus, you can connect the wearable to your phone to enable features like Bluetooth calling and music playback.https://www.notebookcheck.net/KESHUYOU-GT5-smartwatch-with-Bluetooth-calling-and-alleged-blood-pressure-sensor-available-worldwide.668147.0.html
How the heck do these Chinese smartwatches that pop up on NBC measure blood pressure? As per my understanding you need an inflatable cuff for that. I've looked up several smartwatches featured here with that function. Their pages usually mention this feature in the title. It is not described or even mentioned in the product description.
@anan
Smartwatches use two technologies to measure blood pressure: electrocardiography(ECG) and photoplethysmography(PPG). For smartwatches using the ECG technology, a sensor at the back of the watch records the timing and the strength of the electrical signals that make a heartbeat. PPG technology uses a light source and a photodetector to quantify volumetric deviation in the blood flowing through the arteries.