I’ve just moved my setup from a Raspberry Pi 4 to a HA Yellow.
I’m amazed by how easy this has been.
(On the scale of beginner to expert I would be well towards the bottom end.)
My advice would be to read the HA instructions here: https://yellow.home-assistant.io , and also watch this excellent video from Lewis Barclay (Everything Smart Technology): https://www.youtube.com/watch?v=zqQ-a6n6lX0
I would recommend first backing up your installation, downloading this backup, and then closing down and disconnecting the old system before powering up the new Yellow.
I also downloaded a backup of my zigbee dongle settings, but found that I didn’t need this.
I plugged in the dongle before setting up the Yellow and was pleasantly surprised when all my devices appeared after the main backup was restored.
I followed the advice from Lewis to first create a basic set up on the Yellow and then restore the backup that you had previously saved.
And that’s it! 