Nope. These radios are part of the theft system and have the original car's specs and VIN as part of their programming. If you swap or cut into the wrong cables, you won't be the first Cadillac owner with a completely dead car.
Any GM dealer or shop owning a TECHII tool should be able to clear the VIN from the new unit. Some dealership are doing-it as a curtsey service (very few) but any of them will ask you for a legal proof of purchasing. They will also ask you for the donor vehicle VIN although I don’t know why since is not required.
Keep in mind you can ONLY replace EXACT same part number radio (with some exceptions). But as a general rule if on one says along with THEFTLOCK, BOSE and on the other does not then it will CERTAINLY NOT work. The part numbers are common (wit some considerations) between different models (EXCEPT Catera).
Tuesday (next week) I will visit a dealership for the exactly same reason.
If you plug the new one in the car it will say on the screen something like this:
You might also have the “THEFTLOCK activated car might not restart” message on the dashboard plus a THEFTLOCK codes something like this:
B1271 - Theft Lock Enabled - VIN does not match expect value
B1780 - Theft Lock Enabled
You can drive the car with the code (and the messages) until you get to the dealership.
To test a HU you can simply plug it to car data port (under the steering wheel near the parking brake). The following pins to be connected:
HU Pin F1 to Data connector Pin 16 (12V+)
HU Pin E16 to Data connector Pin 4 or Pin 5 (GND)
HU Pin E6 or Pin F6 to Data connector Pin 2 (Data)
Now all the THEFTLOCK discussion is for nothing if the unit is brand new never connected to another car.
But yeah, Sub is pretty much right, for the average person the best answer is NOPE.