I use a Logitech K400 Plus with my ShieldTV, unifying receiver is plugged into a USB hub. After tapping any key or touching the mouse pad my TV, Shield and Sound bar all wake and then I use the "sleep now" option from the power menu and everything shuts off. (HDMI-CEC is at play for all devices)

Typically you will need a subset of these devices that specifically handles infrared signals and can learn from your existing remote. Check Amazon for 'Android wifi learning remote'. I got one for ~$US 17-18 bux