A USB stick reports itself as a USB stick. A device you set up to report itself as what you want reports itself as what you want. The only thing a computer can talk about a device is what the device reports itself. That’s how computers and peripherals work. The computer provides power and the peripheral tells the computer about itself.

So if you make a device that reports the exact same information as your other mice then yeah the computer thinks it’s the same mouse. But it’s not usable as a USB then. It can’t do other stuff.

Yes your friend plugging in a USB will get them in trouble, cause they can exfiltrate data.