What a fun project! I’m using MagicMirror a little differently - not as a mirror, but as a component of my home automation system. MM runs on a Pi that is connected to my AV receiver/distribution system, and it broadcasts content to five or six different TVs/monitors all around the house.
This all started because my home automation setup includes an alarm clock - at the specified time, various lights through the house slowly ramp up from zero, and the bedroom TV (and others) turn on and play streaming music. I was using an Apple TV as the source for that, but when it streams music the video just displays either album artwork or a screensaver. I wondered if I could maybe have the screens display some more useful information - especially a weather forecast - and stumbled on MM.
My home automation server software (Indigo Domotics) publishes HTML “control pages” which can display status information for anything it can contact/control. That’s how I get the door lock status and inside temperature (from the thermostat); it displays in MM using iFrame. The automation server runs a radio tuner app called Radium and an Apple AirPlay tool called Airfoil to stream SiriusXM to a client app installed on the Pi that is running MM; the server pulls track/artist info and puts that in a different control page enclosed as an iFrame.
It’s stretched to the edges because of some overscan issues I haven’t completely worked out yet, but on the house TVs it looks swell. I’ll probably make a few more layout tweaks - had to increase the font size on pretty much everything since it’s usually viewed from a distance.