You just need Toppik or similar with a matching color and nobody could tell... Used by stylists for movie stars all the time, including females. I bought a bunch of colors for my photoshoots as many models have their hair destroyed from all the stuff they are using and fixing it in Photoshop is unnecessarily time consuming (OK, GANs are coming, so it might be instant soon...). It looks pretty natural in studio lights unless you zoom in significantly.