Bios boot options -- find command that is being run

I have asus mb with amd bios. In the boot options list in the bios that are 4-5 boot alternatives listed.

One option is: Windows Boot Manager(P1:TOSHIBA HDWE140)

I would like to find out what command this option is running, i.e., what is it loading and where? Can’t find any help in bios to get this info unless I am missing something.

I want to change grub to run this command using grub customizer. I’ve lost a runnable windows boot in grub.

thanks, tom kosvic