The special features are hard to replicate. Hue sync won't work for example. That's why I still use the hue hub in addition to a zigbee stick for non-hue lights and switches. But if they want a login I'd rather drop hue sync and just add the lamps to my zigbee stick.

I looked this up a while back. Someone wrote code to try to replicate it in homeassistant on their forums. If I recall correctly, it didn’t work quite as well as the hue version but I haven’t have a chance/reason to try it yet. Maybe someday soon.

Not all Philips bulbs actually, only Hue. They have another line called Wiz which uses wifi.