I followed the same procedure on a RPi 4 8Gb with SSD drive. And I have the same (minor) problem:
The boot time is extremely long (about 30 minutes).
Beside that the system works flawlessly and is extremely fast! HA restarts are very fast too (they are by no means reboots as one might think.)
So after all I found that I hardly ever reboot and I can ignore the problem for now and hope that the long boot times will disappear with the stable version of HA OS 5.