normally the Adrenalin Driver offers the option Switchable Graphics - to select either the integrated or the discrete graphics card for a specific application - but the latest driver for my NUC is missing that option. So the NUC always using the VEGA RX M GH discrete graphics card...
(The Hades Canyon has intel hd graphics and the radeon vega graphics chip build in)
I also heard that this lovely NUC reached EOL (EndOfLife) status at intel - is a more up to date version of the converted "Radeon Graphics Chip to Intel Branding" Adrenalin Driver is somehow affected by this. i guess the product is still quite new and it clearly should benefit from future driver support.
Thank you. That answered all my questions. In addition I can confirm from my side that this NUC so far operates just fine with the latest Adrenalin RX Vega 56 drivers from AMD's official page. In case somebody wan'ts to use more up to date graphics driver than the "UI translated" ones on the intel download page for the NUC8i7HVK.