The earlier the stage of boot, the more you have to duplicate functionality provided by the later stages of boot. If /boot is encrypted, then the GUI is GRUB (the boot loader), and it is very limited. If /boot is not encrypted, then the GUI is talking directly to the frame buffer (video memory). This code has to be put into the kernel image or initial RAM disk. There is no GNOME or Wayland at this point, because they are in the partition that has yet to be decrypted.
It is easier to leave more of the operating system unencrypted if you want more friendly passphrase entry GUIs.
The ext4 file system supports file level encryption. Maybe it is possible to encrypt just /home and /tmp, but that leaves /var and swap unencrypted. Swap can be disabled, or enabled with encryption at a later stage of boot with some extra code.
So I guess the good news is that even if we do not get full disk encryption (without requiring a USB keyboard), we will at least be able to encrypt our files.