How to disable mouse at dualboot

Question

I have made a setup using dual-boot. When the PC boots it waits 5 seconds and then boots to standard Windows 10 Pro. No problem, it works.
However, I would very much like to disable the mouse in the 5 seconds pause. I hope using regedit and changing something can do the trick. The result I want: Choose OS using only keyboard.
If you ask why: If someone, by accident, moves the mouse in the 5 seconds delay, the countdown stops.