xubuntu 19.10 fails to install with /boot on different drive - grub-install error

[Ralf Mardorf]

On Fri, 22 Nov 2019 16:37:48 +0000, Chris Green wrote: 
>Since I do have a bootable system does this mean [snip]

I didn't keep this in mind. You even don't need to install GRUB by the
new install. I'm a syslinux user and even when I used GRUB 2 a long,
long time ago, I edited grub.cfg manually.

You either could add the needed grub.cfg entry to your working
install's grub.cfg manually or run

http://manpages.ubuntu.com/manpages/xenial/man8/update-grub.8.html

OTOH I don't know if this "os-prober" thingy does recognise the NVMe
drive.

Remember, you are the human guinea pigs:
https://lists.ubuntu.com/archives/ubuntu-users/2019-November/298670.html

You got just one reply and it wasn't a help, just a #MeToo:
https://lists.ubuntu.com/archives/ubuntu-users/2019-November/298671.html