This is so duh, I’m sort of bewildered that it’s not a standard thing.
If you remove the remote from its spot on the coffee table, the TV, stereo, and whatever device the remote is linked to all turn on, and the lights dim automatically. If you replace it, they all shut off and the lights come back on.
Could use RFID or something similar to make sure that it’s actually a remote and not a stray tortilla chip. Could use a battery instead of cables & keep everything wireless. The gesture is the same, though: Pick up the remote to watch something, put it down to stop.
-Josh