My project is a soil moisture sensor, powered by a battery, that is charged with a solar panel, sending data over ethernet-over-nRF24l01 radio (parts under $25, without housing $?) to an MQTT broker (RPi). I have this running on an older Nano and radio.
Now I'd like to use the Nano Every. My question is pretty much the same closed question at Sleep Mode Atmega4809 Arduino Nano Every
LowPower.h provides a simple way to power down the non-mega CPUs. Granted the max sleep time is 8s, but you can string those 8s together with only being powered up for a few uSecs between them.
The "LowPower.h" library doesn't work on the Every. The closed topic "Arduino Nano Every" links to "avr-libc: <avr/sleep.h>: Power Management and Sleep Modes". The information on that page is inadequate and makes the useless reference "Refer to the datasheet for the details relating to the device you are using"
The documentation I have found has a lot of "if you screw this up you can brick your device" and a lot of language referring to CPU registers, a place the inexperienced should avoid. This last link talks about turning off various timers and interrupts, but doesn't tell one if they get turned back on after returning from sleep.
I just need a little hand holding.