Luanti (formerly Minetest) has a new release out, which finally adds an in-game settings menu so you don't have to quit your current game to adjust things.
I believe, you could in principle use any Blender model, although I’m guessing, they’d need to match in terms of animations. I’m not deep into either Luanti modding or Blender, so not sure how it works together, but here’s some documentation describing it: https://docs.luanti.org/models/using-blender/
I have no idea, if it’s any good, but apparently this exists: https://content.luanti.org/packages/JALdMIC/aw_personaje_anthro/
I believe, you could in principle use any Blender model, although I’m guessing, they’d need to match in terms of animations. I’m not deep into either Luanti modding or Blender, so not sure how it works together, but here’s some documentation describing it: https://docs.luanti.org/models/using-blender/