It is nearly impossible to reason with someone who does not believes that well-fitting N95 masks are not effective-- pretty much 100% effective-- against the virus. If masks didn't work, all of our doctors would have gotten COVID before the vaccines were available.
The virus is smaller than the gaps in N95 mask fibers, that is true. However, the fibers have an electrostatic charge which capture the virus. Here is a pretty cool explanation of how they work. If this doesn't convince anyone, I don't know what will.
You’ve seen them a million times. You might be wearing one right now. But do you know how they work to block a potentially virus-carrying respiratory blob?
www.wired.com
I literally stake my life on them. In the spring, I saw infected young adults immediately after they got out of quarantine (and when they were probably still contagious) and I know I wound up seeing a few who tested a positive a day or two after I saw them. I did limit indoor exposure time when I could, but if someone had something really private they wanted to discuss, we'd work indoors for 10 or 15 minutes in a tiny room with terrible ventilation.