Preview

It looks like this

  themes/miku-grub # grub theme
  󰈙 LICENSE.txt
   PKGBUILD     # 'makepkg -si' install theme miku-grub on arch
   grub.cfg     # Don't directly use, unless you know what're yon doing.
   preview.jpg
  󰂺 readme.md

Install

makepkg -si or copy theme to /usr/share/grub/themes

# edit GRUB_THEME in /etc/default/grub like:
sudo nvim /etc/default/grub
GRUB_THEME="/usr/share/grub/themes/miku-grub/theme.txt"

# customize template grub.cfg in repo or normally do this:
sudo grub-mkconfig > /path/to/boot/grub/grub.cfg