I have just got a NUC8i7HNK but it fails to boot a USB stick with Linux on it. I am attempting to install XenServer. I have played with a number of boot settings to no avail.
I have an HVK but I would imagine that most of the configuration is the same between these two models. Most importantly in order to help you we need to know some details such as how did you create the bootable usb? Did you use rufus? If so what settings did you use within rufus, UEFI and MBR, UEFI only? Did you use dd? Did you use Ubuntu startup disk creator? What version of XenServer are you trying to install? Details like this go a long way for config and install issues like this. I did find some people who have mentioned keyboard stuff in relation to versions of XenServer and older NUCs: https://discussions.citrix.com/topic/380706-running-xenserver-7-on-intel-nuc-nuc6i3syk/ https://discussions.citrix.com/topic/380706-running-xenserver-7-on-intel-nuc-nuc6i3syk/
I found that when I was trying installing anything with legacy boot enabled or raid enabled even if it brought me to the live disk selection screen after I selected I'd get nowhere (black screen) really really fast. Once I disabled legacy mode in the BIOS I started to at least get GParted to get into the GUI and creating partition tables and resizing and stuff if I went in with the 'standard VGA something something' selection in GParted live disk boot menu. I also had some serious Intel Visual Bios issues until I flashed the BIOS to the latest version, it would freeze up almost every time I went in to fork around with the settings. If you haven't done that yet that might also help out with life in general.
Did you create your Linux USB drive as a EFI/GPT drive? Hades Canyon does not support Legacy so you need to make sure your flash drive is setup correctly. Also, I don't think Linux is supported officially so driver support may be spotty.
I use fedora linux on my hades canyen but it will not work out of the box.
For full support you need kernel 4.18 and mesa 18.1 both are actually in development so you will not find any distribution who deliver this. Maybe in the autumn.
I did this (i hop I can remember all points):
1. update the bios. On my was 0028 installed but that shows options that not supported like legacy boot options. this diapered if you install a newer one.
2. make an UEFI Boot stick, lock on your distro for the preferred solution to do it.
3. Boot from USB (you must first activate in bios). with F10 you get the boot menue and you can see which boot disk the bios discovered.
4. on the Distro boot menu you have to chose an "Alternate Graphical mode" or set the boot parameter nomodeset. this is needed because the VEGA M is not supported and you need to boot with framebuffer mode.
5. so I could install Fedora 28 and boot to the desktop without problems.
But this is a slow Framebuffer mod so you can't play games or such things.
If you can/will compile a new kernel there could be full support.
6. I Update to fedora 29 (this is the development branch) at the moment it support mesa 18.1 and kernel 4.17
This kills your freembuffer support after that you have to work in the console and you need to add the boot parameter "nomodeset 3" if not you end up always in black screen
7. Checkout the drm-next-4.18-wip kernel compile and install it.
8. Download and Install the VEGA M Binary firmware
9. Boot from the new compiled kernel.
Maybe in a month or so fedora 29 will update to kernel 4.18-rc then there should support for VEGA M when you update to it.
On my systems I did some Preference tests and started a game and it works pretty good for so a small box.