There should be an easy way of seeing what and how many games of your library are working on different platforms, e.g. in case someone with Windows wants to migrate to Linux.

This could be achieved by adding a "Linux" option to the drop down menu in your library to Windows and Mac client. This has another advantage, you could simulate a migration to Linux, to see if he actually can give up on some games that are not compatible. Moreover, it should show your favorite and most played games and highlight them,w hen they are available for Linux.