Onlyfun 1.Is it possible to unlock user profile without unlocking owner profile?
The practical answer to that specific question is no.
The problem is the question, tho.
Or to better say, the problem is the reason you think the question is relevant.
Let me ask you this:
If your laptop has two encrypted disk, one for data and one for the OS, are you able to decrypt the second (data) disk without decrypting the first (OS) one?
This is not a second layer of encryption, this is just an inconvenience, because the second disk is not bootable and you need your OS to mount it. You would still need the first (OS) disk to be decrypted even if the second disk was not encrypted.
This is what is happening here, you are logging in with the first (owner) user, just because some information about the OS are there, and there only.
This is not a security feature, it's merely an inconvenience, which is forcing you to login with the owner user before logging in with the second.
If somehow you had these OS information available to every user, you just needed to login with whatever user you wanted.
Onlyfun Let skip theoretical 'if' since we have physical devices to implement methods you claim.
The setup I offered you as example is not theoretical, as this is my current setup on a physical PC, so we can skip all the "if"s, whatever that means.
Onlyfun Such practice is very likely to mislead and cause false conclusions.
Onlyfun Speculations about future can't prove Current state of things
I would agree if those were my words, but they weren't.
Those are quotes from the developers themselves, I kind of think they know if that is intended behaviour or not.
At the very least they would know if they planned to change this behaviour in a few years.