There is a power button on the newest apple tv 4k. It doesn't look like they have that one in their DB yet.

The remote itself doesn't have google voice built in. If you have a google device already in your home, you can link your sofabaton account, that way, instead of using the remote, you can use the google assistant on your other device. For instance, you can say, Hey Google, tell sofabaton to turn on the TV.

I've got this exact receiver and I'm able to control everything just fine. The one thing I had to fiddle with a little bit was the placement of the ir blaster. I really had to try a few different position to get it to register commands. I have my receiver and all devices in a cabinet though, to I was prepared to have to mess around with the blaster placement a bit. You can give that a try if you haven't already.