Any company allowing the unregulated use of these on their devices has a information protection and most likely also an IT security problem. Even more valid for any government security or law enforcement organisation.
BTW: GDPR prohibits this in the EU.
Medically the nose is far better equipped to deal with pathogens, so breathing through the nose would be better, both in (to “filter”) and “out”(to get right of stuff). More important, nevertheless is proper hygiene - wash your hands, fellas. And do not touch your face,but especially not your nose and eyes after you have been exposed to germs.
Besides that there is literally zero evidence for anything else - the very limited research in some breathing techniques has all been debunked sooner or later.
If you want to be sure,wear a proper N95/FFP2 mask. Proper means: Tight fitting, the right size for your face (not the cheap ones from the truck stop).