About zombie broken head retopology need some suggestions

Hi! I made this zombie broken head with head bone inside.

I have a problem now. In the future, I need to have a close-up shot of a broken head in the animation, and the zombie need to rig.

But the head part of zombie model has so many bumps and bumps, retopology takes a lot of time, but use remesh takes a lot of faces. Can anyone give me some suggestions to make the workflow faster and try to reduce the number of faces?