It used to be possible, with some hackery, to filter library games by operating system using some hidden HTML. Basically there was some unused code for OS icons, with some client-side scripting it was possible to hide all games that had a (hidden) Windows icon, for example. My Mitch app relied on this to show owned Android games, but this has been broken for some time now.
Some proper filtering would allow me to see owned mobile games again without relying on dirty hacks like that.