HQP does have a Linux version but the embedded version doesn’t support Roon, meaning you need to load a gui to use the desktop version.
Loading a basic Linux on the MacMini to run RoonServer headless and loading HQP on the Xeon Jason mentioned in this other thread sounds like a pretty interesting architecture to me.
Of course, then you’ll probably want to load a gui onto the Xeon, so you could still be updating Windows there …