That plays randomly my music through the google music app or something?
Any app like that so I can turn genres/playlists into live channels?
Also is there anything like that for youtube that can turn youtube channels/playlists/my subscriptions into live channels?
Lastly can I somehow add SPMC as a live channel? I don't care for pseudoTV just add SPMC main screen into live channel app.
I use Spotify instead of Play Music so I couldn't tell you how it is in that case, but Spotify has built-in functionality for what you ask. You can play a certain genre as a radio and you can just shuffle one of your playlists or saved songs.
As for YouTube, no, it doesn't have that functionality. Mind you, the YouTube has not seen a new version for a long time so I would not hold my breath over new functionality, unfortunately...