The mounts listed would appear to be on the system hosting the chroot, and do
not include the root file system that you want grub to work with.
Presumably, you have a partition somewhere that contains the root file system
that you want to work with in your chroot. First, mount that partition:
mount /dev/your_partition_containing_rootfs /mnt
Then, if you have separate partitions for things like /var and /tmp and so on,
mount those too. Eg.:
mount /dev/your_partition_containing_var /mnt/var
Don't forget to mount your EFI partition at /mnt/boot/efi, if booting UEFI.
A good source for information regarding the file system on the target rootfs
would be /mnt/etc/fstab.
Mount /sys, /proc, /dev, and /run. Eg.:
mount --bind /dev /mnt/dev
When complete, chroot into the root file system you have mounted, and do your
grub business:
chroot /mnt /bin/your_shell
On Sunday November 14, 2021, Stefan Blachmann wrote:
Here is it:
541 33 0:50 / /home rw,relatime shared:309 - zfs rpool/home rw,xattr,posixacl
557 33 0:52 / /opt rw,relatime shared:317 - zfs rpool/opt rw,xattr,posixacl
572 33 0:53 / /root rw,relatime shared:325 - zfs rpool/home/root
rw,xattr,posixacl
