passwords accept hash, instead of Base64
from autounattend.xml to powershell, user accounts are managed by base64encoded strings. This is ... frankly ... terrible, as it's not even technically encrypted. Want to see that admin password default in the autounattend.xml file? simply run:
$nextstep = [System.Convert]::FromBase64String("<put it here>")
$finalstep = [System.Text.Encoding]::UTF8.GetString($nextstep)
Please allow hashing/salting to be used for password conifguration, be it from an unattend.xml file or as an option when creating new accounts to allow at least modest protection when passing credentials.