

If your privileged user doesn’t have a password, in some cases this could lead to any program being able to elevate their privilege quietly, unlike UAC.
I think this is the most important part. There really isn’t any protection against random processes trying to do some version of exec sudo $0 except for the fact that it requires a password.
This is probably the main reason every mainboard has TPMs now, since all common operating systems (Android, iOS/MacOS and Windows) do it.
From what I heard the Ubuntu installer offers a version that doesn’t suck (if secure boot is enabled at install time) so using that is probably fine, but I would beware of trying to DIY it since it’s easy to do incorrectly, most guides are wrong, and you will likely end up with easily bypassable encryption.