I have Garmin Edge 530 and and Bontrager Ion Pro front light and Flare RT backlight.
Garmin 530 edge has some support for those lights out of the box. However the thing it lacks it a datafield that shows both lights battery state.
I managed to make a datafield that shows both light states and current modes using LightNetworkListener and also periodically reading the state and battery.
The only problem I'm experiencing is when the battery is critical the light automatically changes it's mode to some kind of power save to but does not report it to Garmin.
I wonder if there is a way to check this somehow but I'm afraid that it's the Bontrager lamp fault. I've heard that some higher models of Garmin have Connect IQ apps for Bontrager lamps.
You can see here that the battery is critical but the selected mode is 100%/Override but actually the light does not have this mode. I was planning to have a timer started the moment the light enters this battery saving mode because it lasts about 30 minutes until complete shutdown.