I’m having the same issue with geekpi on HA. I’m using the POE hat version
https://wiki.52pi.com/index.php?title=EP-0241
and my POE doesn’t have any under voltage issue.
Most of the time the homeassistant restart works fine but 50% of the time reboot issued from HA cause nvme to be undetected. I have to unplug the Poe cable from pi and back in
I have tried adding boot_delay but still the same issue