What data transmitted as part of "pairing" is suitable for implementing a vendor lock-in?

Question

Bluetooth

The LG TV with webos has BT, but it only works with "native" headsets. I read a little on the wiki and have not yet understood - what exactly can the manufacturer be attached to in order to weed out "extra" devices even at the mating stage?
And, if people who know BT will answer this question, then I’ll immediately ask - this parameter can somehow be changed in the existing device (or in general, are there those that can be changed on free sale)?

Answer 1

For example, by MAC address.
The vendor in it is encoded by the first bytes.
As a rule, it cannot be changed on any peripheral like headsets.

Answer 2

Such protection can be done at any level. For example - in the BT standby mode, the device sends out connection setup packets (advertising pockets) so that others can recognize it. These packages have a field that can be configured by the manufacturer. There he can indicate his ID and filter by it. This ID is issued by BluetoothSIG (special interest group) and costs $5k.
You can change it in the finished device if you only write your own firmware.