So today i've got my low profile 2.54 headers for the Pi from Aliexpress and that means that it is time to connect those three LEDs left on primary cap alongside of battery level indicator.

Since UPS HAT already occupies some GPIO for it's purposes (these are marked red), i've chosen another set of GPIOs to hook up cap leds (marked in green)

Some assembly pics:

And if everything is done correctly, after booting basic GPIO toggling python script, you may be greeted by this (new leds are to the left of the power switch):

Some use cases are probably to indicate things like WLAN status, battery low, messenger unread blinking... You name it.