Currently, Roon works as the designers have created it. This may or may not fit your needs. You can look for a similar existing feature suggestion in
or write one if there is none.
It may not be likely that it will be implemented, though, in particular if it involves something akin to folder browsing. Actual folder browsing has been discussed to death and will never happen.
Roon has many other ways to browse the library and you will be much happier with Roon if you (learn to) use it the way it was meant to. If this is not for you, it’s also OK, though.