I built this in 2019 and its been rock solid, and figured i should post some pictures of what i started with and where i’m at today :)
I must say this mirror is probably the most used item in our house, since we share a family calendar it’s our goto to know what we are doing each day. My wife loves it and everyone that sees it is blown away:)

What i ended up doing is taking a mirror and frame we liked and dismantled it by removing the actual mirror. I then replaced it with two way mirror and built a frame to hold the TV (42") and mounted it the visible frame around the mirror.

Final Product:

To make a clean look i cut out the wall, removed a stud in the middle and did a french cleat system to hang the mirror with a flush look.

Dismantling the TV:

Building the frame to support the TV: