Hi, Mii expert here. Turns out, the NPCs in TLoZ:BotW use an advanced version of the Mii format. This means that with modding, you can inject Miis into the game. :)— i'm alice (@HEYimHeroic) January 4, 2021
Thinking about opening commissions for Mii injects, both screenshot/images of your Mii and mod downloads! pic.twitter.com/8NfVr4zyqA
A Twitter user by the name of @HEYimHeroic has figured out how non-playable characters are generated in The Legend of Zelda: Breath of the Wild. It has been discovered that the faces of these characters use a modified version of the coding used to create a Mii. This means that it is possible for modders to change the faces of these characters by loading in data from a Mii.