I'm asking about the FDE option Ubuntu provides upon installation.
I'm not familiar with how Ubuntu does it, but here's how I understand Truecrypt/Veracrypt on a Windows machine works:
There is a bootloader, a partition with some Windows files, the Windows OS itself and possibly any other user-generated partitions.
Now from what I understand Veracrypt will encrypt everything listed above, including the bootloader and create its own bootloader, which will be the ONLY non-encrypted thing on a particular disk. Once you enter the password on the boot screen it will start decrypting the Windows bootloader, then the OS itself and so on - whatever is requested.
I'm not familiar with how an Ubuntu/Linux system is partitioned and encrypted, but from what I've read I was left with the impression that not everything (i.e. the WHOLE disk with every partition on it) is encrypted by default - is that correct?
/boot
as well. See https://askubuntu.com/questions/729673/ubuntu-full-disk-encryption-with-encrypted-boot – user68186 Dec 11 '19 at 15:45