I’ve checked google, tortoise table app, here.... everywhere. It’s such a common tree I am surprised there isn’t more info on it. I know other animals eat the leaves.
The list of trees that have known edible leaves is quite short (and hackberry isn’t on it as far as I know). I am sure deer probably eat it but they can tolerate a lot of the tannins and other nasty compounds in tree leaves. If I had one of these trees in my yard it would be taken out immediately, as they are very short lived, disease prone, and yet get big enough to cause real damage when they inevitably die and fall down.