Can Roon show music unique to your own library?

I was wondering: is it possible to let ROON show only the music that is unique to your own library and not (in any version) as well availiable on Tidal or Qobuz? Because I would like to know how my library compares to the Tidal and/or Qobuz ones.

I don’t believe so.
You are asking Roon to show only those albums which have no streaming service alternatives. Roon queries its streaming services database in real time when you set on the album (you may briefly see a circular moving arrow to the right of “credits” before it shows “versions” (if there are any)). At that point Roon knows if there are 0, 1 or more. If more, it populates the versions tab.

As far as I can tell, Roon doesn’t keep this information so there is no attribute in the your library database you can focus on.

You could consider starting a feature request.