These are a good idea too but they need headlights to work. So, they aren't sufficient. (Note that it's generally a legal requirement to have a rear light at night.)

They can be dim. Also, many people don't have pedals that will accommodate them.

These are the same idea as pedal reflectors but brighter (much brighter) and work for any pedal. You do have to remember to put them on. But they work in all directions (unlike pedal reflectors).

https://www.amazon.com/Jogalite-Cros...s%2C115&sr=8-2

There are two general types of reflective material (used like this). This works when wet. The other, which looks gray in marketing material doesn't work when wet.