Yes, time of flight is what UWB measures. But Bluetooth isn't suitable for measuring TOF to a useful accuracy. (I'm not sure what the Watch unlock feature is using.)

There’s two ways to triangulate, another is using two antenas and attempting to estimate the power of the signal source.

In practice this sucks more than one would imagine. In a cluttered environment all you get reliably is close, near, far, somewhere else. Because you have 10-30db multipath fades and attenuation exponents are on the order of 2.5 to 3.5

You can spoof that too, with a relay. In fact, just putting the relay transmit antenna in the expected place should give the right ratio of RSSI.

Seems silly to imagine, but it is possible and I didn’t consider that.