Thanks. I have ordered an Intel NUC6CAYH. My google search leads me to [this page] for Ubuntu
It sounds like HA is mission-critical to you. What I do (and I posted this in another one of your threads) is possibly something you should consider.
Instead of building a dedicated x86 machine to run Homeassistant, build a Proxmox virtual server and run HomeAssistant in a container. Create containers or virtual machines for your other critical home services. Then add a second Proxmox machine and build a cluster. It takes 10 minutes after your first Proxmox machine is set up to install and add a second machine to the cluster. Then you can migrate containers/vm’s from machine to machine with the click of a mouse in less than a second. I have my pfSense firewall in a VM on my cluster and can migrate it from node to node without losing a single ‘ping’ packet to an internet host.
Raspberry Pi’s are not really intended for mission critical applications.