blood pressure

Blood pressure is measured by constricting the blood flow by applying pneumatic pressure to an arm cuff or a finger stall , then gradually releasing it, noting the pressure at which the pulse is detected and then the pressure at which the device becomes too loose to detect the pressure. You have to be at rest to take it it to get a sensible reading. and keep still while it's being measured, and the device should be more or less at the level of your heart. You can see from all this that it's not something that you will be able to do with a watch.

I'd be interested to know how it can do it - perhaps since the watch can detect the pulse to get the timing it can also make some attempt to measure the strength - of course you wouldn't get the diastolic, and I'd want to be very cautious about the accuracy.

No, you would need a device also to measure the blood pressure.

A hardware device that measures blood pressure.