That is possible. I was considering releasing the PSD layered file as a separate purchase once I accumulated enough layers. The same goes for the Busts but it's a bit more tricky. Would require users to be familiar with photoshop/gimp editing and layers. So debating if that's something I should list or not.
One of my favorites artists whos Patreon I am releases a spritesheet for every component (base/body, tops, bottoms, facial hair, hair, items/weapons) with all the animation frames. You just have to place them on top in the correct order. It's really simply an grants a lot of freedom.
Btw: Do you have a Patreon including your work?
If you are interested in pursuing the layers idea - I'm a web dev and would be happy to build a character generator using your graphics that you can then release.