How do I get the very first boot messages, before the decryption of the system and before uvesafb is loaded, smaller? I tried:

GRUB_GFXMODE=1024x768

GRUB_GFXPAYLOAD_LINUX=1024x768

and

GRUB_GFXMODE=1024x768x8

GRUB_GFXPAYLOAD_LINUX=1024x768x8

and

GRUB_CMDLINE_LINUX="video=VGA-1:640x480"

the same as hex code (is supported according to sudo hwinfo --framebuffer),

in /etc/default/grub

and

  set gfxmode=${GRUB_GFXMODE}    

  set gfxpayload=keep

  load_video

  insmod gfxterm

  insmod vbe

in /etc/grub.d/00_header. And of course, always sudo update-grub2.

The letters are still very big. Some of the above possibilities even result in a black screen before uvesafb is loaded.

Version: grub-mkconfig (GRUB) 1.99-12ubuntu5