Separate Libraries?

If you store the libraries in different locations then Focus/Inspector/Storage Locations and Bookmark is simplest. This won’t work for Tidal though.

Otherwise you can make user tags for your respective music and Focus on them. You can tag multiple albums using select (right click), select all (ctrl-a) and deselect.

Completely separate libraries, however, needs two databases and Cores (two licences). If you really hate 80’s electronic …

Others have asked for improved multi-user tools also.