Creation options
From Scratch is for direct editing. Get Help is the faster guided route where the game asks simple questions and helps create a resident.
Nintendo describes expanded customization across facial options, face paint, body details, voice, personality, and quirks.
Import and transfer limits
Nintendo Support says you can create residents based on faces of Miis registered on your Nintendo Switch or Nintendo Switch 2 console.
It also says you cannot directly import Miis from other software such as Miitopia, and game-created Mii data cannot be transferred out to the console or other games.
FAQ
How do I create a Mii?
Use From Scratch for manual creation or Get Help for a guided flow based on simple questions.
Can I draw on Miis with face paint?
Yes. Nintendo materials list face paint as part of Mii customization.
Can Miis be Non-Binary?
Yes. Nintendo Support lists Male, Female, and Non-Binary as Mii gender options.