On an unrelated topic, Daerandin discovered that.. I mean, I discovered that installing PlayOnLinux on SteamOS required a whole lot of dependencies that are not present in SteamOS. So what I did was enable Debian stable repositories. I made sure to read up a bit first, because I didn't want any Debian packages to possibly replace SteamOS packages. Thankfully you can define repository preferences, so that identical packages get pulled from SteamOS repositories and not Debian repositories.
I have given one game a try in PoL on SteamOS and it runs without issues. My next task is to see if I can make the SteamOS GUI launch PoL shortcuts. I know you can do this, but I want to see if I can create such Steam shortcuts via scripts.