MagicMirror² seems to be easy enough, and give a good result. There also exists a ton of modules.
Bought a 15x20 photo frame and mirror foil. Cheating a bit with the frame – instead of making it from scratch, I decided to use a prebuilt frame meant for photos.
The mirror foil failed completely. It was black instead of silver, which makes it hard to use as a mirror. Ohh well.
Assembled the display (display, display driver board, display control board, and cables), and connected it to the Raspberry PI with a USB cable and a HDMI cable. The display is powered with 5V from the USB, so only one power cable is needed in total.
Display received by mail.
Finally ordered display from Pimoroni.
Hardly a session, but I spent some time looking for a display. After a lot of thinking, I want a small display that can use the Raspberry PI as a power source. Several exists, but most of them are touchscreens. Which would be a complete waste.
I will probably order https://shop.pimoroni.com/products/hdmi-8-lcd-screen-kit-1024x768 – an 8 inch display powered by USB. It also has a decent resolution – more than enough to display some text.
Research day. Set up a parts list over some of the things needed to get this going. Finally decided to build a small mirror instead of a larger one so the display can draw power from the PI itself.
Also got hold of a UBS keyboard (only have the wireless ones at home!) and a micro HDMI connector. Got the PI booted and set up. Installed the magicmirror.builders software without trouble and booted the default config.
Got my Raspberry PI kit in the mail. Also bought a Sunfounder kit with a bread board and a few parts.