Hello,
Grub can ignore all or only certain OSes that os-prober detects by
setting up the desired behaviour in /etc/default/grub
from the grub info page:
[...]"
'GRUB_DISABLE_OS_PROBER'
Normally, 'grub-mkconfig' will try to use the external 'os-prober'
program, if installed, to discover other operating systems
installed on the same system and generate appropriate menu entries
for them. Set this option to 'true' to disable this.
'GRUB_OS_PROBER_SKIP_LIST'
List of space-separated FS UUIDs of filesystems to be ignored from
os-prober output. For efi chainloaders it's <UUID>@<EFI FILE>
"[...]
:-)
