Unable to puzzle through grub.xen_pvh

[David Kowis <david@xxxxxx>]

I started here: 
https://wiki.xenproject.org/wiki/Xen_4.12_RC_test_instructions#PVH_domU_boot_via_grub2
I was able to build and copy over the resulting built component. I then 
proceeded to change an existing vm that booted PVH with the 
kernel="/path/to/grub.xen_pvh" instead of bootloader="pygrub"
It worked in that I got a grub command prompt, which usually happens 
when grub doesn't know what to do. I feel like I'm really close!
my cfg:
=============
name="hass"
type="pvh"
vcpus=4
memory=2048
maxmem=4096
#bootloader="pygrub"
kernel="/usr/local/bin/grub.xen_pvh"

# Enable pv on hvm drivers
xen_platform_pci=1

vif = [ 'mac=00:16:3E:DE:AD:78, bridge=xenbr0' ]

disk = [
  
'phy:/dev/disk/by-path/ip-10.255.255.2:3260-iscsi-iqn.2005-10.org.freenas.ctl:xen-lun-35,xvda,w'
       ]


# usb passthrough for the zwave stick
usbctrl=['type=auto,version=2,ports=4']
usbdev=['type=hostdev,hostbus=2,hostaddr=3']
=============

There is a grub.cfg in /boot/grub/grub.cfg on that disk. It's a standard 
ubuntu 18.04 vm, which I've built a kernel with the PVUSB drivers on it. 
Trying to get that kernel to boot easily, and a more real grub 
environment would help solve it.
Thanks!