HDMI standards allow plugged in devices to control the power state of the TV. e.g. my Apple TV will turn the TV on when I press a button on the aTV remote and will turn the TV off when I turn the Apple TV off.
Audio is a separate challenge, I'm not sure what you'd do there. Do computer monitors have eARC outputs? None of the ones I have do. Again if you had an Apple TV you could pair it with a HomePod (or pair of them) to avoid the issue but that's a niche solution.
Audio is a separate challenge, I'm not sure what you'd do there. Do computer monitors have eARC outputs? None of the ones I have do. Again if you had an Apple TV you could pair it with a HomePod (or pair of them) to avoid the issue but that's a niche solution.