@felmue Your measurement for ESP deep sleep + Imu.sleep is accurate. My device is drawing the battery down about 5-7% per day, which is roughly 5ma.
I tested your patch. Unfortunately it doesn't seem to work once the RTC countdown timer is set. If one uses Power.shutdown, the Rtc timer is bypassed in the code in favor of the ESP timer since M5UNIFIED_PC_BUILD is not defined (why?).
Rtc.setAlarmIRQ does work in it's integer form, if followed by Power.powerOff. I could not get Rtc.setAlarmIRQ to work in its date,time form.
Your patch does turn off the PaperS3 otherwise, but with the ESP completely powered down its timers aren't functional.
So I think we're stuck with ESP deep sleep for now. It would be interesting to see the code for the PMS150G. I'm not sure what all that FET logic around it is for, maybe an AXP192 wouldn't fit on the board. (And why a USB chip that would prevent the device from frying when plugged into a USB PM port wasn't included.)
I tested skipping M5.begin but the PaperS3 would do nothing. Tested with Display.init and it worked, but battery readings were undfined. Tested that with M5.Power.begin and battery readings were still undefined, probably because board_t isn't set.
Something besides the IMU is sucking that power though, the BMI270 should use less than 1ma even when fully awake. The PMS150G uses only a few uA when running, I don't think it ever turns off.