If this is true for Bluetooth
It is likely true for wifi and cellular radios as well.
In before anyone says "I never enable Bluetooth so I'm safe"...
Researchers at the University of California San Diego have shown for the first time that Bluetooth signals each have an individual, trackable, fingerprint. In a paper presented at the IEEE Security and Privacy Conference last month, the researchers wrote that Bluetooth signals can also be tracked, given the right tools. …
Yep. Any radio signal received by a receiver of sufficient fidelity can probably be identified from its little manufacturing variations, though a lot of knowledge of the specific transmitter design is likely needed. Though if the signal transmitter is purely analogue there is is likely a lot of instability in the signal anyway due to temperature, etc. It's digital radios like Bluetooth that are going to be most likely to be identified this way, where things like timing features are traceable back to a single component (a crystal oscillator generally)
What gets interesting I think is where does this tech go? If someone commercialises it, would it be usable by, say, shops to glean insights into customers? The tricky bit is the law. Here in the UK there is a section of the wireless and telegraphy act 1948 prohibiting reception of signals not intended for oneself. Tech like this creates a grey area. By enabling a Bluetooth beacon, one is often doing so on the understanding of anonymity. It probably isn't legal, at least in the UK, to unpick this anonymity by measuring signal features that the transmitter has no intention of a receiver accessing.
What's also interesting about UK law is that it is not offence to possess equipment capable of doing this, but actually using it can be.