I have not. I would guess limit current draw on GPIO use. Shut down unused areas (not sure what that would be). If you can shutdown USB.
Kevin Darrah from YouTube has lots of Arduino power saving mode, but a microprocessor is different in that it does not need to run an OS that is not intended to be shutdown and does not boot fast.
3 of 3 people found this helpful
Turn off Bluetooth if you are not using it.
rfkill block Bluetooth
1 of 1 people found this helpful
I spotted the following which suggests the main Linux CPU can be shut down and then woken using the MCU
Here's some stuff
And even more stuff here