Hiding behind or even within an illusory barrel or dresser or other item is fine to me. That makes sense and seems well within the scope of the power.

I agree with BurgerBeast that this seems pretty complicated to pull off at-will in any location. But then, wizards do have high intelligence scores, so I don't know. It certainly strikes me as something more involved than the proponents are letting on.

But the mirror... I just don't see it. I don't even think it's a question of whether illusions reflect light. Here...

Wave your hand in front of that mirror and tell me if you see your reflection.

An image of a mirror does not have the same reflective properties of an actual mirror. Yeah, you can see it, just like you can see the mirror I posted above. But you can't see your reflection, because it isn't an actual mirror, just an image of one. Minor Illusion creates images, and those images do not behave like the real objects.