Hello, on previous piCore versions the disk activity led would blink rapidly during boot, so I could tell my headless Rpi is booting fine.
on 15.0 the led does not blink rapidly, it stays on during the boot process then turns off when disk activity ends.
I ended up adding this line to my bootlocal.sh to give me the same visual clue that boot process has completed:
echo heartbeat | sudo tee /sys/class/leds/ACT/trigger