Adding a full wolf/dog head shape would be a bit tricky.
If it's just wolf/dog themed it could be done, as long as it doesn't go outside the base-model's proportions. 🤔
We're planning to add some customization options once the bulk of the character model is in place (both for Woolly and the male models).
In an ideal world, we'd like to let people upload their own texture swaps, but that still needs a bit of research (especially on the web version side).