Thanks for the review! I'm glad you're liking it so far! All of your questions are great and I'll try and answer them as best as I can:
"Everything is fine, until you add Prefabs or nested ones: looks like it requires some extra manual work to have it working"
Can you elaborate? It should work fine with prefabs, but if it doesn't I'd love to fix/improve it.
"I'm pretty sure it has to be on the same transform that contains a mesh, but some people could assume that it could work like, putting at the base of a complex hierarchy of the base."
Deformers can actually be anywhere in the scene and on any GameObject. Prefabs will obviously lose references to deformers that aren't also in the prefab, but there's nothing I can do about that. If you haven't already, check out the Getting Started video! It explains some interesting features of deformers that may not be immediately apparent.
"How does it handle instancing? Is it safe to create a prefab with a deformable inside?"
Yes! Each deformable instance will have a unique mesh.
"would be cool if Deformer asked about tweaking the original mesh asset to be marked as read/write, which seems to be an implicit prerequisite"
You're totally correct! I'm actually working that right now. Some things just slip through the cracks ¯\_(ツ)_/¯ It will now show a warning box and log a more informative error.
"I'd suggest to work on creating some documentation"
I'm gonna be working on that for sure! I agree, it's very important.
