Some hardware manufacturers provide proprietary software for some of the functionality that's been mentioned. For example, NAD (and a couple of others) use BluOS, which indexes stored files and integrates with a boatload of streaming services/radio channels, e.g., Tidal, Qobuz, Idagio (classical), Radio Paradise (mentioned earlier). It also has multi-room control; some NAD models also include DIRAC room correction. Other hardware vendors have different solutions.
How well any of these compare to Roon I don't know -- just wanted to mention that they are out there for those buying certain hardware brands.
BTW, someone mentioned Primephonic integration: Primephonic doesn't integrate with much of anything other than Airplay, BlueSound (but not BluOS), and Sonos. They've been saying "real soon now" for a long time, but so far, no action. Pity because it's an interesting choice for classical music..