Indeed! I doubt there are studies on this, but I wouldn't be surprised if wearing an N95 with a full enough beard is equivalent to not wearing a mask at all, or to wearing a t-shirt cloth mask.
Whenever I'm about to be in a place with people, I try to remember to fully shave that morning, so there's not even a day or two's worth of stubble preventing an N95 seal around my nose and mouth.
There are studies; ultimately, nothing with COVID is binary - it's levels of protection, and even with a beard there are a lot of "depends" based on the length of beard, fit of mask, and proper wearing.
I do find that one kind of KN95 fits great even with my beard (which is short - ~5mm). I trim next to the nose so I have a good fit there, and my side/bottom are short enough that for the most part mask seems to "dig through" the hair and contact skin, kinda like the Studded tires dig through snow to get to ice.
But again, I'm aware that my protection is lower than if I shaved. Personal risks assessments are personal, mine is that I work remotely, am on video calls 6+ hours a day, and shaved I look like a 12 years old :). Meanwhile I very rarely go out, and if I do go out for groceries biweekly or so, and not at all now during omicron, distance + mask + booster provide a reasonable protection.
I got rid of my beard before a big (vaxx and mask required) convention in DC last weekend, wore an N95 to the best of my ability, and tested negative (PCR) more than 24 hours after, and I am still feeling fine.
The difference between N95 and cloth masks is so big that we should just treat cloth masks as no masks.
There's some truth to that, but if we try to mandate N95 masks and no longer allow cloth masks, that'll destroy the mandate altogether. The majority will simply ignore it.
When the pandemic started, I had several of my friends jokingly tell me that it was time for my beard to go if I wanted to get the full protection of an N95. I jokingly told them that if it was between me loosing my beard and getting covid, I was getting covid (in my 20's for context).
Granted not the smartest decision but given my risk factors and the fact that I've never not had a beard since I could grow one, so people would likely not even recognize me without one. And two years on I have yet to be infected so I'll count my blessings as a stoke my glorious beard.
Whenever I'm about to be in a place with people, I try to remember to fully shave that morning, so there's not even a day or two's worth of stubble preventing an N95 seal around my nose and mouth.