Due to the kernel options problem, which I'm not clear would be solved by removing grub/grubby, I decided to try to use systemd-boot to bootstrap GRUB.

The only requirement I can find is that it needs to be on the same drive as the ESP partition, so I'm going to convert the 1GB NEW_ESP partition I created to a grub /boot partition and see if after I install systemd-boot to the original ESP partition, grub will be found.

Thanks,

Richard