When money is no object, you have to get a commercial display (like this [0], w/ 55" class (54.6" diagonal) Edge-Lit LED IPS Digital - $1350MSRP). Otherwise, something like a Vizio P series (which has an embedded chromecast) is good if you turn-off the wifi radio and/or never give it your AP's credentials.
I grew up with a TV that would immediately turn-on when you pressed the button (you could even hear an audible sound from the TV set), and the cable TV remote (it was separate in the 80s too) could change channels at 4-5 per second (this is when channels surfing was born because they would render so fast).
Vizio has a line of OTA-free displays, but they still have a Linux kernel. This is a good start, but going back to whatever RTOS they use to have would be better.
[0]http://www.lg.com/us/business/commercial-display/displays-tv...