Alright. Time to write an update…
I have installed Ubuntu Studio 24.04 with X11 on my Asus GR8, specs here:
And oh boy 
No problems whatsoever as far as color management is concerned. XNView MP, digiKam and darktable all work just as desired.
Nvidia 750Ti (…reported as 860M for some reason? Who knows what’s inside, but it’s almost the same GPU, so whatever…) works out of the box apparently 
I’ll be honest I was not expecting that… well, at least System Monitoring Center reports Nvidia activity during darktable exports, so…
I did a very scientific comparison of performance to my Dell laptop running an i7-11370H (4C/8T) + Iris Xe 96 by pressing CTRL+E at the same time on both machines and … the Asus is noticeably faster 
Where do I find the log file after running -d perf tho?
Nvm, it is in the terminal window 
So far it is only installed on the HDD that the PC came with, but since it works very well, I might shove in an SSD and reinstall, since I haven’t done much to the system beyond some basic testing…