B&O did this in the late 1980's and developed a TV set with true zero power off consumption, though the set itself was a Phillips Vestel chassis ( IIRC) inside the box, with a nearly standard Phillips IR remote control, and a slightly modified Phillips microcontroller board, with just a few tiny changes made to the firmware ,and a single hardware change.
How they did it was to put in a power switch with a 12V solenoid coil to release it, and then put in into the OSD menus as power option, which would either put it intro low power regular Vestel board standby ( power supply would turn all outputs down to a low voltage, the microcontroller would use the I2C bus to disable the tuner, horizontal and vertical oscillators and mute the audio amplifier IC, the power supply running in a hiccup mode to maintain a low voltage on all the rails, the micro being powered from the 36v audio rail via a high voltage rated 7805 regulator) or in the true off state the micro would put the Tv into power off, and then trigger the coil on the power switch to disconnect power from the mains input entirely.
There was also an auxiliary contact on the switch, which made only while the switch was pressed, not while it was latched. This was connected to the microcontroller so it could, on power up, tell if the power had gone out ( thus start up the set in standby) or if the power switch had been pressed, and turn on the set like it had been commanded on via the remote control.
These were touted for use in places like hotels or such where they could be off for long periods, and you wanted the power saving, or for those who did not want the red standby light on all the time. Free with this control came a timer, so you could turn off the set automatically at night after you fell asleep.