Well I can provide more details.
What I did was I did download debian-live-11.5.0-amd64-kde+nonfree.iso from here: https://cdimage.debian.org/cdimage/unofficial/non-free/cd-including-firmware/current-live/amd64/iso-hybrid/
I Put the ISO image on an USB stick and I did boot my Macbook from this stick.
However WLAN does not work with this image so you need a wired LAN connection on your Macbook.
Then you download efibootmgr by:
sudo apt update
sudo apt install efibootmgr
Then you can modify your EFI NVRAM entry by:
sudo efibootmgr -c -L “Garuda” -l \\EFI\\Garuda\\grubx64.efi
Take care. you need two backslashes for the path not forward slashes and it need to be two of them as shown above.
However, this is the example when you have a standalone Garuda installation on your Macbook otherwise you may have to provide. a different disk and or at least a different partition by the -p option.
With this the Macbook did boot into grub after a restart, however you will end up on the grub command line. So there are of course several possibilities how to fix this. What I did was i entered the garuda instalation USB stick and on “Garuda Welome” I choose “Garuda Boot Repair” and there I did choose the second option “Repair GRUB configuration file”.
And another reboot now from disk and you should be done.