...covering some of the holes on the side of a shotgun mic...
Directional mics do indeed use multiple ports to create the directional pattern. It's the same principle as directional subwoofers.
Both subs and (most) mics are too small compared to the wavelength that they work with, for a single aperture to be anything other than omni. So they use multiple apertures that interfere with each other, reinforcing in one direction and cancelling somewhere else.
So for a different example, a rapper that likes to cup the mic is actually destroying the directional pickup pattern by blocking the rear ports, making it omni instead, and *that* can cause a floor wedge to feed back when it wouldn't have otherwise, *even if the mic is pointing away from it*.
As for the sound or tonal quality changing, that's also a possibility. Part of the electro-mechanical-acoustic design of a mic is the frequency response too, and as a passive device, everything affects everything else. Even for a phantom-powered mic that has a pre-preamp built in, it's still passive before that amp, and so a lot of the same things still apply. The built-in amp does give an opportunity for the designers to correct things that are easy to correct electronically, so that the physical design can focus on other things instead, but because that correction is fixed, it still doesn't change the possibility of changing the sound when you mess with the acoustics.
Whether that sound is okay or easily correctable, is another question. You might just have to try it, with a good ear AND a good EQ (OBS's EQ is probably not good enough), and see what you can come up with.