I actually use Photogrammetry for all my Characters, to some extent anyway. I usually only do hands for photogrammetry in order to capture all the micro-detail correctly, everything else I usually sculpt. Even though I usually use my own scans I’ve also purchased a few pre-cleaned scans from Ten24. You might want to check them out, even though it’s a bit expensive as a result of USD currency conversion (Their store site uses Euros.)
But anyway, I personally tend to avoid facial captures because they are often too difficult to get acceptable results from a single camera’s work. Hands are easier to work with certainly. And I personally make sure to only one finger per chunk and then merge the resulting chunks by dense point cloud alignment in Agisoft. I usually get pretty decent results. With that being said, I’m also fortunate enough to have set aside a particular space in my workshop for Photogrammetry and tuned the lighting conditions properly.
As far as polycount goes, what I usually tend to do and create a low-res mesh in Fuse that roughly fits the sillhoutte of the photogrammetry hand. And then I reproject the high-res detail onto the new mesh, export it with vertex color baked in, and then bake out all the maps in Substance Painter. I could certainly make a video of my workflow if people are interested.