On Pinephone, the RTC(has alarm support) is in the SoC and is always powered by PMIC even when the phone is off. PMIC can be configured to power up on interrupt signal, and SoC can be configured to pulldown the interrupt line on RTC alarm.
On Pro RTC is inside PMIC directly.
HW can do it. Alarm app just has to use the HW correctly.
On Pinephone, the RTC(has alarm support) is in the SoC and is always powered by PMIC even when the phone is off. PMIC can be configured to power up on interrupt signal, and SoC can be configured to pulldown the interrupt line on RTC alarm.
On Pro RTC is inside PMIC directly.
HW can do it. Alarm app just has to use the HW correctly.