Here's a question to give you a sense of scale: Which of the following would be brighter, in terms of the amount of energy delivered to your retina:
1. A supernova, seen from as far away as the Sun is from the Earth, or
2. The detonation of a hydrogen bomb pressed against your eyeball?
Applying the physicist rule of thumb suggests that the supernova is brighter. And indeed, it is ... by nine orders of magnitude.
...Sounds like I should buy one of these IoT alarms so that I know to stay away from the window :-)