Would this work for Dorico and if so how well?
I think that “how well” would depend on several things, most importantly would be how accurately you can touch the screen to place things. Additionally, much would depend on your video card and the inputs that the TV would have. For example, if the only output from your computer to the TV is HDMI the image on the TV will look very grainy since the maximum resolution of original HDMI is 1900x1200. With dual-port HDMI the resolution can be up to 2560×1600. DisplayPort is 3840×2160 which would probably look very very nice on a 55" TV.
How much do you think you would use touch-screen input in Dorico, compared to the midi-keyboard/computer-keyboard/mouse input with a standard display? I have a touchscreen monitor and I find that I’m doing almost everything with mouse/computer-keyboard/midi-keyboard in Dorico.
I suggest you consider carefully before spending the kind of money necessary to get what the setup shown in the video would cost. It would be a shame to spend all that money and then find that you’re using the touchscreen functions less than typical computer input methods.