So, I have my desktop configured with two drives, one has a regular windows install on it that I need to play games with my brother. That works fine.
My second drive originally had Debian on it. But I wanted to also install EndeavorOS. At this point in time, all 3 work, but the selection process to access each system is painfully different.
To access Windows, I just boot from cold, and hit enter or wait for the timer to run out on Windows booting. But when I hit esc to cancel booting Windows, it brings me to Debian's GRUB selector. But I think when I installed EOS I used the default settings, and I believe it doesn't use GRUB by default (systemd). So the GRUB menu I get only has Debian or Windows. If I hit 'esc' again I am brought to the grub> command line. Here the only thing I know how to do is type "exit" and it closes this grub> cmd line and opens another, very similar one. I type 'exit' again and I am finally met with EndeavorOS's boot selector (I believe this is systemd?)
Now I know from my first dual boot with windows/Debian that I am pretty much stuck having windows boot loader run first, so my perfect scenario of having a single selector off boot is a pipe dream, but I'd love to remove a few of the GRUB cmd steps in getting to EOS (chances are I will only need the Debian system for very specific tasks. odds are I will end up removing it) I'm guessing if I would have told the EOS installer to use GRUB it would have potentially added EOS to the GRUB selection screen? Is it possible to rectify this without wiping and reinstalling with different boot loader options?
Try rEFInd. It's pretty good about detecting OSes and auto-populating its menu, and it has a pretty easy conf file format otherwise. Installing the refind debian package mayybe will also register it with the system firmware, I don't recall. If not, it can be set up with efibootmgr (which is not the most pleasant program, sadly).