You could remove the coating, but that is a big pita as you can't use anything too rough or it disturbs the grain. I sandblasted the interior of my doors to maintain the grain. I then painted with reduced epoxy, mixed as a sealer. That makes it very thin, and it doesn't fill the grain. Keep in mind reducing the epoxy shortens the recoat window so you want to make sure you pay attention to that.
Even if you aren't going to remove the edp, you'll need to scuff it. Use a grey (fine) scotch brite or equivalent, then white epoxy mixed as above, then your color. I can't find any pictures of my door grain in the reduced epoxy, but here is the grain after the interior color.