It already worked in Debian setup. It had some advantages on that system. battery life, heat etc.
I got it to work with this grub.d/40_custom
search --no-floppy --set=root --file /EFI/custom/apple_set_os.efi
chainloader (${root})/EFI/custom/apple_set_os.efi
boot
Credits to
https://github.com/0xbb/apple_set_os.efi
https://gist.github.com/stefanocoding/c6dbf4489f330021bd9335d655c9fbbf
the combination of their grub.d/40_custom files worked.
ty for your help also.