That isn't a function of it being N95, it's a function of the mask having a proper nose piece (usually wire or a thin strip of metal). You bend it to conform closely around your nose, and it keeps the air from escaping up around your nose, and thus prevents fogging. There's a lot of other masks that accomplish this (Vogmasks are quite nice). The masks my sister-in-law makes (based on the
ragmask pattern) accomplish this perfectly well, with a slot on the top edge for a piece of copper wire.
Most commercial N95 masks have a vent, which is great if you're, say, sanding something and trying to avoid breathing the dust, but kind of defeats the purpose for pandemic use, since your breath flows out freely through the vent. Unless you tape over the vent from the inside.