Plymouth
Package
yay -S plymouth
Configuration
Add plymouth hook in mkinitcpio.conf after base and udev:
/etc/mkinitcpio.conf
HOOKS=(base udev plymouth ...)
List plymouth themes (reads /usr/share/plymouth/themes):
plymouth-set-default-theme -l
Set plymouth theme, e.g. BGRT:
sudo plymouth-set-default-theme -R bgrt