If my phone was not powered on could shutdownmonitor still work and show on my Google activity list?

Welcome to Android Central! Shutdownmonitor is a system app, so there's nothing shady about it, in case you were worried.

When you say "not powered on," do you mean you completely powered the phone off, or just put the screen to sleep?
 

Forum statistics

Threads
955,451
Messages
6,964,840
Members
3,163,282
Latest member
dobebmo1