You don't activate a pkg, you install a license for the title you installed from a pkg, so it's perfectly fine... now, I'm not sure if you can rename the licenses
Sure!Could I rename that to say mgs3.pkg, install it and then use the non-renamed RAP to activate.
Sure!
(Note how most homebrew doesn't conform to the full titleid naming standard )
Only because nobody [reasonably known] packages them with DRMTrue, but real homebrew doesn't always require a RAP
Only because nobody [reasonably known] packages them with DRM