The workaround I have found at this point is to rebuild grub after migrating to XCP-NG. Adds a few minutes to each VM but I don't have that many.

Boot to live iso in UEFI mode (I used Debian12 given it was a Debian12 vm)

sudo su -
mount /dev/mapper/?????  /mnt 
mount /dev/xvda2 /mnt/boot
mount /dev/xvda1 /mnt/boot/efi
for i in /dev /dev/pts /proc /sys /run; do sudo mount -B $i /mnt$i; done
mount --bind /sys/firmware/efi/efivars /mnt/sys/firmware/efi/efivars
chroot /mnt
grub-install /dev/xvda
update-grub
exit
shutdown now

I'm using LVM so adjust the first mount to match your root partition.
I shutdown so that I can remove iso and boot when I'm ready.

Hope this saves somebody a bunch of frustration in the future.

Which is fair but I have moved 3 bios Debian 12 without issue. I have tried 2 different Debian 12 with UEFI and both have failed with the same error.

I use open-vm-tools on them. I'll try removing it but cannot start the vm for a while because something locks the vmdk on the esxi side after doing the xo migration and I have to either reboot the host or wait a while.

I'll try building a new uefi debian 12 vm and see if it happens from a clean build.