> the external HDD for the Xbox 360 has the "secret sauce" / binary blobs that allows this to work and emulates certain Xbox games
IIRC, that's _partly_ because it requires Microsoft to pay a licensing fee to Nvidia for the original Xbox GPU, so baked that cost into the cost of the hard drive rather than the console itself.
Yep, the external HDD for the Xbox 360 has the "secret sauce" / binary blobs that allows this to work and emulates certain Xbox games.
Similarly, the Xbox One also has the backwards compatibility library to emulate 360 games, but doesn't require an extra accessory. Each game download contains its own wrapper of the 360 emulator.