Hi,
I've been using LibreElec for quite some time now. It's a great KODI distribution! 
If you're running a x86-NAS it doesn't make much sense to run an additional machine for KODI (power consumption, cable clutter).
I suggest to enable the KVM guest kernel modules and 9p filesystem kernel module for shared folders in LibreElec to be able to run it in a KVM virtual machine with GPU passthrough.
Have phun with LibreElec! 