Since April 2022, Raspian or Raspberry OS does not come with a default
pi user anymore. To create a user without a gui or using their own imaging tool, you need to create a file called
userconf on the boot partition, just like you would when you Activate SSH on a Raspberry Pi.
The file should contain a username and password combination, where the password should be encrypted.
The password can be encrypted with the following command:
echo 'mypassword' | openssl passwd -6 -stdin