yonder
I see them as IMU trackers that can get location when in view of the headset. That means with 2 on you legs and 2 controllers in your hands, your arm and leg positions are (somewhat) tracked. I think just how the quest controllers can go a few seconds without be seen by the headset without any major tracking innaccuracies, these trackers will do the same thing.
OMG it has iphone cameras.
This actually seems pretty practical given it uses the same system the controllers are using. It might not be tracked all the time, but should be if you look down or are lying down. Also, it sounds like they will use software to estimate position when .
This appears to be an advert dissed as an article. Also, I know my bike lights already emit light in all directions by making the shell transparent.