It's a bold idea, but it worked. This might mean character mods won't be limited to humanoids in the future.
This time, I mainly tested issues with face models.
For Genshin Impact:
The face model cannot be modified; doing so causes it to shatter immediately. It also cannot be deleted, as that freezes the game when switching to the character. Additionally, since multiple characters share the same face model, deleting it causes other characters' faces to disappear as well.
For Zenless Zone Zero:
The face model cannot be modified; if modified, it will shatter once the character starts running. However, it can be deleted, and the work above is an example of that.
For Wuthering Waves:
The face model can be modified and partially deleted, but it cannot be removed entirely. You must keep at least one triangular face.