The big thing appears to be moving the user metadata into the home directory itself rather than it being around the system, and enabling home folder encryption, which has been like... a single button press feature on Windows since like Windows XP. Sounds like a step forward.
The same key which encrypts the volume decrypts the metadata, but they use different IVs.
You could assume that most systems the key would be secured with the TPM so this won't be much of a big deal to the user, but otherwise when they try to login it would prompt for this password first.
I'm not sure I understand the appeal. What does "putting user configuration inside the home directory" mean in this context? Is there a file with the UID, GIDs (primary, secondaries), GECOS, etc?
What is put inside the homedir?
* https://systemd.io/USER_RECORD/
You'll enjoy the bit about the umask. Yes, this is short on details of where all of the privileged and secret stuff lives.