That's really cool! I've been working on a modified version of Feendrache's animator https://feendrache.itch.io/mana-seed-character-animator-for-unity. It aids in building animations and attaching them to animators. One big thing I've added so far is support for blend trees in the animator. It's a ways off from being releasable, but I'd like to ask the author to formally release their code under a permissive license so I can release mine. But it very nicely fills the gap between Sprite Importer and Paper Doll.