Three more questions
1. Can I use transparency with textures with alpha channel?
2. Can I use some kind of specularity/roughness maps?
3. Can I use shape keys (alias blend shapes, alias morph targets)? That would be nice for facial expresions especially if the number of bones is limited. A face rig would use up a lot.
The Problem is, I started to make a very very simple face rig and now i have 96 bones and I would need much more. Even if you upgrade to 100 bones that would not be enough. With shape keys I could do facial animation with a less bones. The collada format *.dae can save shape-keys. I used them in Unity and Godot.