Ich sehs' schon kommen: In grenzregionen sammeln sich dann ein haufen arme Schweine, die auf dem Papier nicht in dem einem und nicht in dem anderem Land sind.
You can use an online tool to look up the Bluetooth [1] or Wifi [2] MAC of the device. If it's espressive you've got one of their chips. That doesn't guerantee that it's not one of the others they make. You can also open up the device and look for the esp32. They almost always look the same with their metal can ontop.
Someone correct me if i'm wrong, but it looks like it's not the big deal the original blog post makes it out to be.
To issue those undocumented HCI commands one either needs to hijack a computer/soc/mcu that is connected to an esp32 with HCI UART transport enabled or put malicious software on the esp itself.
The mac spoofing might be interesting for people building hacking tools, however.
I guess most people who want to use a domain as their username aready have that domain.