Mailing the story:
winesapOS is another way to get something like SteamOS on desktop
While Valve has still yet to produce an official installable image of SteamOS 3 for desktops, as always the community provides and another worth looking into is winesapOS. Another I covered is HoloISO, which tries to stick quite closely to SteamOS 3 but winesapOS aims to be a bit more than that.