I’m sure this isn’t hugely helpful, but I found that if I went into the Hue app and deleted all of my lights and switches then went into home assistant and did a zinger add, almost everything was discovered right away.
Determining what each device was still a manual process. That’s where your automation suggestions would help.
Additionally, I noticed after doing this that there were several Zigbee groups that I hadn’t seen before. They had generic names. They might have been Hue groups that were automatically imported, or something completely unrelated.
Hope this helps a tiny bit with your journey. It’s an admirable and daunting plan.