Is there a way, or could it be implemented, to make various sub libraries?
When your library gets expanded with quite some albums it would be good not to scroll through the whole album list but to go immediately to e.g. Jazz or Classic Chamber or Brittish Blues to find your music. I guess more music fans should have this problem.
Have you tried sorting on Genres , you can set Roon to use your Genre tag if you wish but it’s all or nothing and leaves you to manage the genres
the other way may be to arrange your library into separate folders for the High Level split say Jazz then import the multiple folders into Roon then use Focus > Storage Location
Just click on Genres. Even if you are not maintaining any genre tags or other metadata then I would be surprised if roon isn’t auto-segmenting your library already. To get finer control, you will have to start adding/editing genre tags that make sense to you:
If you have a library mostly consisting of local files, in my experience this is the preferred way to go. When creating sub-libraries which you want to temporarily disable, you are not dependent on sub-genre hierarchy, nor automatic album identification (which is not always flawless).
For example, for the sake of smoothly browsing through classical albums, I most of the time end up with disabling the back catalogue of opera and sacred music recordings, sometimes even all stereo recordings.