I know a bit about masks. Minor p/l, I have experience with the M25A1 Biological/Chemical Mask. It's an NBC protective mask designed specifically for armored vehicle crewmen. There's a very real, and practical reason the military insists on you being clean shaven. Any amount of stubble, let alone the beginnings of a beard, will interfere with, and compromise the seal of your mask.
The rubber material that goes against your skin has to have a totally smooth surface in order to achieve a 100% seal. Any small compromise in the seal will let in whatever nasty shit you're trying to protect yourself from, and the mask, and you, are defeated. You might as well not even carry the fucking thing. When you don your mask and exhale to clear it, you then put your hand over the intake port and breathe in. If the mask sucks down hard around your face and you cannot draw any air, you have a good seal.
I knew the entire covid mask thing was bullshit early on because nobody even mentioned this issue. You have to have the proper filtration elements, and you have to have a mask (and face) capable of a proper seal. Anything less, and you're just pissing into the wind, and hoping to stay dry.
Also, filtration elements in any mask become saturated, and have to be changed out on a regular schedule. The mask itself also requires regular cleaning and preventive maintenance. Never heard a single fucking word about these subjects either.