Ahhh the old Apple lock in at play.
People have success with Mac Mini’s.
Personally I would not run a Roon core on a Mac Mini. Not after having experience with it. I switched off a Mac Mini to a Small Green Computer ST with a Bryston Pi endpoint. You could get a SGC ST with a Sonore endpoint to run the Roon core and play ripped files. especially the optical Rendu
The boat anchor is the Apple Music. Maybe do a trial run with Qobuz or Tidal music service and see if there classical offerings have your content. Here is a link to how Roon manages Classical, advance to about the 4:10 mark.
https://www.youtube.com/watch?v=5N3RZM_JfL0
If you can find a Roon endpoint that uses another of your 6 digital besides USB input you could use a iPAD mini and go USB into your ML.
It was a happy day when I said goodby to Apple music and my mini in the chain.