

Atleast for android and Bluetooth. Not an absolute matter protocol thing, but probably “normal android allows that only woth google signed app”. Some OS access thing and so on. “You don’t get to access that Bluetooth matter discovery call mode etc. without official sign off, security hurdur”.
Since matter has ways to connected fully without Bluetooth depending on device. Bluetooth is just the easy simple way, instead of having to hunt for pairing QR symbols or number codes. Go to the other device makers app to activate pairing mode or generate one off pairing codes and so on.
Ikea pairing is Zigbee standard group binding via touchlink initiation. What is different is Home assistant, which doesnt really handle Zigbee groups.
If you mean zigbee group binding, in my experience Home Assistant doesnt handle Zigbee groups well. There is technical capacity and group manager, but to me it seems it doesnt correctly bind all of the action clusters and so on. Plus most finally the UI is very confusing etc. (That or I’m dumb and can’t get it working right)
Home assistant handles grouped devices primarily inside its own logic and talks to them as individual devices. Which leads for example to stuff like non synchronous action. I don’t think Zigbee groups either guarantee synchronicity, but it is pretty instant since it is single mesh wide broadcast of “whole group this, do this”. Where as Home assistant send say ten different messages to ten different Zigbee devices. Thus there is delay and difference, when each device receives their individual command.
Most dedicated Zigbee hubs like trådfri and hue use actual Zigbee groups. When moving devices between “rooms” or whatever each call it, it sends actual configuration message of “change your internal registered group identity” to the lamps, remote controls and so on.