If I use the same Mag Evolution Device on two characters, does it unlock account-wide like Accessories, Hairstyles, Basewear, etc do? Or would I need to use the device on every single character I wanted it on?

From what I can find, consumed Mag Evolution Devices are character-bound with no way to unlock them account-wide.

EDIT: I have just personally confirmed that using the same Mag Evolution Device on multiple characters does not unlock it account-wide.

That's unfortunate. Thanks for testing for me.