Vertical progressbar in Grub 2?

Hi! I’m trying to do a remake of the graphics in opensuse 15.2 Leap.
What I want to do is making the boot menu look like in SuSE Linux Professional 7.3.
So I want to put a vertical progress bar on the left side of the Grub 2 boot menu.
I have no prior experience of programming.
How to achieve this?

Implement vertical progress bar support in GRUB2.